| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| The public API function BIO_new_NDEF is a helper function used for streaming
ASN.1 data via a BIO. It is primarily used internally to OpenSSL to support the
SMIME, CMS and PKCS7 streaming capabilities, but may also be called directly by
end user applications.
The function receives a BIO from the caller, prepends a new BIO_f_asn1 filter
BIO onto the front of it to form a BIO chain, and then returns the new head of
the BIO chain to the caller. Under certain conditions, for example if a CMS
recipient public key is invalid, the new filter BIO is freed and the function
returns a NULL result indicating a failure. However, in this case, the BIO chain
is not properly cleaned up and the BIO passed by the caller still retains
internal pointers to the previously freed filter BIO. If the caller then goes on
to call BIO_pop() on the BIO then a use-after-free will occur. This will most
likely result in a crash.
This scenario occurs directly in the internal function B64_write_ASN1() which
may cause BIO_new_NDEF() to be called and will subsequently call BIO_pop() on
the BIO. This internal function is in turn called by the public API functions
PEM_write_bio_ASN1_stream, PEM_write_bio_CMS_stream, PEM_write_bio_PKCS7_stream,
SMIME_write_ASN1, SMIME_write_CMS and SMIME_write_PKCS7.
Other public API functions that may be impacted by this include
i2d_ASN1_bio_stream, BIO_new_CMS, BIO_new_PKCS7, i2d_CMS_bio_stream and
i2d_PKCS7_bio_stream.
The OpenSSL cms and smime command line applications are similarly affected. |
| The function PEM_read_bio_ex() reads a PEM file from a BIO and parses and
decodes the "name" (e.g. "CERTIFICATE"), any header data and the payload data.
If the function succeeds then the "name_out", "header" and "data" arguments are
populated with pointers to buffers containing the relevant decoded data. The
caller is responsible for freeing those buffers. It is possible to construct a
PEM file that results in 0 bytes of payload data. In this case PEM_read_bio_ex()
will return a failure code but will populate the header argument with a pointer
to a buffer that has already been freed. If the caller also frees this buffer
then a double free will occur. This will most likely lead to a crash. This
could be exploited by an attacker who has the ability to supply malicious PEM
files for parsing to achieve a denial of service attack.
The functions PEM_read_bio() and PEM_read() are simple wrappers around
PEM_read_bio_ex() and therefore these functions are also directly affected.
These functions are also called indirectly by a number of other OpenSSL
functions including PEM_X509_INFO_read_bio_ex() and
SSL_CTX_use_serverinfo_file() which are also vulnerable. Some OpenSSL internal
uses of these functions are not vulnerable because the caller does not free the
header argument if PEM_read_bio_ex() returns a failure code. These locations
include the PEM_read_bio_TYPE() functions as well as the decoders introduced in
OpenSSL 3.0.
The OpenSSL asn1parse command line application is also impacted by this issue. |
| A timing based side channel exists in the OpenSSL RSA Decryption implementation
which could be sufficient to recover a plaintext across a network in a
Bleichenbacher style attack. To achieve a successful decryption an attacker
would have to be able to send a very large number of trial messages for
decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5,
RSA-OEAP and RSASVE.
For example, in a TLS connection, RSA is commonly used by a client to send an
encrypted pre-master secret to the server. An attacker that had observed a
genuine connection between a client and a server could use this flaw to send
trial messages to the server and record the time taken to process them. After a
sufficiently large number of messages the attacker could recover the pre-master
secret used for the original connection and thus be able to decrypt the
application data sent over that connection. |
| AES OCB mode for 32-bit x86 platforms using the AES-NI assembly optimised implementation will not encrypt the entirety of the data under some circumstances. This could reveal sixteen bytes of data that was preexisting in the memory that wasn't written. In the special case of "in place" encryption, sixteen bytes of the plaintext would be revealed. Since OpenSSL does not support OCB based cipher suites for TLS and DTLS, they are both unaffected. Fixed in OpenSSL 3.0.5 (Affected 3.0.0-3.0.4). Fixed in OpenSSL 1.1.1q (Affected 1.1.1-1.1.1p). |
| In addition to the c_rehash shell command injection identified in CVE-2022-1292, further circumstances where the c_rehash script does not properly sanitise shell metacharacters to prevent command injection were found by code review. When the CVE-2022-1292 was fixed it was not discovered that there are other places in the script where the file names of certificates being hashed were possibly passed to a command executed through the shell. This script is distributed by some operating systems in a manner where it is automatically executed. On such operating systems, an attacker could execute arbitrary commands with the privileges of the script. Use of the c_rehash script is considered obsolete and should be replaced by the OpenSSL rehash command line tool. Fixed in OpenSSL 3.0.4 (Affected 3.0.0,3.0.1,3.0.2,3.0.3). Fixed in OpenSSL 1.1.1p (Affected 1.1.1-1.1.1o). Fixed in OpenSSL 1.0.2zf (Affected 1.0.2-1.0.2ze). |
| The OPENSSL_LH_flush() function, which empties a hash table, contains a bug that breaks reuse of the memory occuppied by the removed hash table entries. This function is used when decoding certificates or keys. If a long lived process periodically decodes certificates or keys its memory usage will expand without bounds and the process might be terminated by the operating system causing a denial of service. Also traversing the empty hash table entries will take increasingly more time. Typically such long lived processes might be TLS clients or TLS servers configured to accept client certificate authentication. The function was added in the OpenSSL 3.0 version thus older releases are not affected by the issue. Fixed in OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2). |
| The function `OCSP_basic_verify` verifies the signer certificate on an OCSP response. In the case where the (non-default) flag OCSP_NOCHECKS is used then the response will be positive (meaning a successful verification) even in the case where the response signing certificate fails to verify. It is anticipated that most users of `OCSP_basic_verify` will not use the OCSP_NOCHECKS flag. In this case the `OCSP_basic_verify` function will return a negative value (indicating a fatal error) in the case of a certificate verification failure. The normal expected return value in this case would be 0. This issue also impacts the command line OpenSSL "ocsp" application. When verifying an ocsp response with the "-no_cert_checks" option the command line application will report that the verification is successful even though it has in fact failed. In this case the incorrect successful response will also be accompanied by error messages showing the failure and contradicting the apparently successful result. Fixed in OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2). |
| The c_rehash script does not properly sanitise shell metacharacters to prevent command injection. This script is distributed by some operating systems in a manner where it is automatically executed. On such operating systems, an attacker could execute arbitrary commands with the privileges of the script. Use of the c_rehash script is considered obsolete and should be replaced by the OpenSSL rehash command line tool. Fixed in OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2). Fixed in OpenSSL 1.1.1o (Affected 1.1.1-1.1.1n). Fixed in OpenSSL 1.0.2ze (Affected 1.0.2-1.0.2zd). |
| The OpenSSL ECDSA signature algorithm has been shown to be vulnerable to a timing side channel attack. An attacker could use variations in the signing algorithm to recover the private key. Fixed in OpenSSL 1.1.0j (Affected 1.1.0-1.1.0i). Fixed in OpenSSL 1.1.1a (Affected 1.1.1). |
| The OpenSSL DSA signature algorithm has been shown to be vulnerable to a timing side channel attack. An attacker could use variations in the signing algorithm to recover the private key. Fixed in OpenSSL 1.1.1a (Affected 1.1.1). Fixed in OpenSSL 1.1.0j (Affected 1.1.0-1.1.0i). Fixed in OpenSSL 1.0.2q (Affected 1.0.2-1.0.2p). |
| During key agreement in a TLS handshake using a DH(E) based ciphersuite a malicious server can send a very large prime value to the client. This will cause the client to spend an unreasonably long period of time generating a key for this prime resulting in a hang until the client has finished. This could be exploited in a Denial Of Service attack. Fixed in OpenSSL 1.1.0i-dev (Affected 1.1.0-1.1.0h). Fixed in OpenSSL 1.0.2p-dev (Affected 1.0.2-1.0.2o). |
| In order to decrypt SM2 encrypted data an application is expected to call the API function EVP_PKEY_decrypt(). Typically an application will call this function twice. The first time, on entry, the "out" parameter can be NULL and, on exit, the "outlen" parameter is populated with the buffer size required to hold the decrypted plaintext. The application can then allocate a sufficiently sized buffer and call EVP_PKEY_decrypt() again, but this time passing a non-NULL value for the "out" parameter. A bug in the implementation of the SM2 decryption code means that the calculation of the buffer size required to hold the plaintext returned by the first call to EVP_PKEY_decrypt() can be smaller than the actual size required by the second call. This can lead to a buffer overflow when EVP_PKEY_decrypt() is called by the application a second time with a buffer that is too small. A malicious attacker who is able present SM2 content for decryption to an application could cause attacker chosen data to overflow the buffer by up to a maximum of 62 bytes altering the contents of other data held after the buffer, possibly changing application behaviour or causing the application to crash. The location of the buffer is application dependent but is typically heap allocated. Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k). |
| Issue summary: The first concurrent use of the same X.509 certificate by
several threads may cause its cached extension data to be freed while
another thread is still using it.
Impact summary: A remote, unauthenticated peer could crash a multi-threaded
TLS client, or a multi-threaded TLS server that requests client
certificates, if the first certificate chains built to the same trusted CA
certificate are built by several connections at the same time. This is a
use-after-free read, which is likely to crash the process, resulting in a
Denial of Service.
CWE: CWE-416: Use After Free
Description: OpenSSL caches the decoded values of a certificate's X.509v3
extensions inside the X509 object the first time they are needed. In
OpenSSL 4.0 this cache is built in two phases: the extension values are
computed while holding a read lock on the certificate, and the results are
then installed into the certificate under a write lock. Because a read lock
does not exclude other readers, several threads can compute the cache for
the same certificate at the same time. Each thread that subsequently
acquires the write lock installs its own results and frees the values
installed by the thread before it, even though that earlier thread has
already marked the cache as complete and may have returned pointers into it
to its caller. A caller still using those pointers then reads freed memory.
Any certificate shared between threads is exposed the first time its
extensions are decoded. In TLS the certificates at risk are the trusted CA
certificates supplied for chain verification, by whatever means, since these
are shared by every connection and their extensions are decoded and cached
the first time a chain is built to them. Certificates sent by the peer are
decoded separately for each connection and are not shared, so they are not
affected. In a TLS client verifying server certificates, or a TLS server
that requests and verifies client certificates, the use-after-free could
only occur if the first chains built to the same trusted CA are built by
several connections at the same time.
FIPS impact: no
The FIPS module is not affected as X.509 certificate handling is outside
of the OpenSSL FIPS module boundary.
OpenSSL 4.0 is vulnerable to this issue.
OpenSSL 3.6, 3.5, 3.4, 3.0, 1.1.1 and 1.0.2 are not affected by this issue.
OpenSSL 4.0 users should upgrade to OpenSSL 4.0.3.
This issue was reported on 27 August 2026 by Tim Becker (Xint.io) and
independently in a public report on 31 August 2026 by aydinmercan.
The fix has been developed by Bob Beck.
-- cut (non-publishing metadata for internal use) --
Reported by: Tim Becker (Xint.io), aydinmercan
Fixed by: Bob Beck |
| Issue summary: The DTLS retransmission logic does not correctly handle
a handshake message write that is suspended part-way through.
The retransmitted message can be read past the message buffer and
the retransmission overwrites the internal state the suspended write
needs to resume correctly.
Impact summary: The retransmitted message can disclose a heap memory
to the peer as plaintext handshake data or cause a crash and a Denial
of Service when the read reaches an unmapped memory region.
CWE: CWE-125: Out-of-bounds Read
Description: DTLS handshake messages can be written out in multiple
fragments, and a write can suspend mid-message (returning WANT_WRITE)
if the underlying transport temporarily cannot accept more data. While
such a write is suspended, the DTLS retransmission timer may
independently fire and ask the retransmission logic to resend an
earlier, already-acknowledged-as-sent message from its retransmit
queue.
The retransmission logic reused the same internal buffer and position
tracking as the message that was still being written, without
resetting the position back to the start of the message being
retransmitted. As a result the retransmission was read starting from
wherever the suspended write had left off, producing a mislabelled
message whose body was leftover bytes from the other, larger message
still in flight - content that was never meant to be sent at that
point, and which could run past the end of the allocated buffer.
Separately, even when the retransmission is positioned correctly,
allowing it to run to completion while another write is suspended
overwrites the same shared bookkeeping that the suspended write
depends on to resume. When the application later resumes the
suspended write (via a subsequent SSL_read(), SSL_write(),
SSL_accept(), or SSL_connect() call), it finds that bookkeeping in a
state inconsistent with the message and aborts the process in
a debugging build.
The fix resets the retransmission's read position to the start of the
message before resending, and skips retransmission entirely whenever a
handshake write is still suspended, deferring to the next call that
resumes it instead.
FIPS impact: no
The affected code is outside the FIPS module boundary. |
| Issue summary: Applications performing certificate name checks (e.g., TLS
clients checking server certificates) may attempt to read an invalid memory
address resulting in abnormal termination of the application process.
Impact summary: Abnormal termination of an application can a cause a denial of
service.
Applications performing certificate name checks (e.g., TLS clients checking
server certificates) may attempt to read an invalid memory address when
comparing the expected name with an `otherName` subject alternative name of an
X.509 certificate. This may result in an exception that terminates the
application program.
Note that basic certificate chain validation (signatures, dates, ...) is not
affected, the denial of service can occur only when the application also
specifies an expected DNS name, Email address or IP address.
TLS servers rarely solicit client certificates, and even when they do, they
generally don't perform a name check against a reference identifier (expected
identity), but rather extract the presented identity after checking the
certificate chain. So TLS servers are generally not affected and the severity
of the issue is Moderate.
The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue. |
| The DES and Triple DES ciphers, as used in the TLS, SSH, and IPSec protocols and other protocols and products, have a birthday bound of approximately four billion blocks, which makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTPS session using Triple DES in CBC mode, aka a "Sweet32" attack. |
| The X.509 GeneralName type is a generic type for representing different types of names. One of those name types is known as EDIPartyName. OpenSSL provides a function GENERAL_NAME_cmp which compares different instances of a GENERAL_NAME to see if they are equal or not. This function behaves incorrectly when both GENERAL_NAMEs contain an EDIPARTYNAME. A NULL pointer dereference and a crash may occur leading to a possible denial of service attack. OpenSSL itself uses the GENERAL_NAME_cmp function for two purposes: 1) Comparing CRL distribution point names between an available CRL and a CRL distribution point embedded in an X509 certificate 2) When verifying that a timestamp response token signer matches the timestamp authority name (exposed via the API functions TS_RESP_verify_response and TS_RESP_verify_token) If an attacker can control both items being compared then that attacker could trigger a crash. For example if the attacker can trick a client or server into checking a malicious certificate against a malicious CRL then this may occur. Note that some applications automatically download CRLs based on a URL embedded in a certificate. This checking happens prior to the signatures on the certificate and CRL being verified. OpenSSL's s_server, s_client and verify tools have support for the "-crl_download" option which implements automatic CRL downloading and this attack has been demonstrated to work against those tools. Note that an unrelated bug means that affected versions of OpenSSL cannot parse or construct correct encodings of EDIPARTYNAME. However it is possible to construct a malformed EDIPARTYNAME that OpenSSL's parser will accept and hence trigger this attack. All OpenSSL 1.1.1 and 1.0.2 versions are affected by this issue. Other OpenSSL releases are out of support and have not been checked. Fixed in OpenSSL 1.1.1i (Affected 1.1.1-1.1.1h). Fixed in OpenSSL 1.0.2x (Affected 1.0.2-1.0.2w). |
| The SSL protocol 3.0, as used in OpenSSL through 1.0.1i and other products, uses nondeterministic CBC padding, which makes it easier for man-in-the-middle attackers to obtain cleartext data via a padding-oracle attack, aka the "POODLE" issue. |
| The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the "Logjam" issue. |
| The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft Internet Information Services (IIS) 7.0, mod_ssl in the Apache HTTP Server 2.2.14 and earlier, OpenSSL before 0.9.8l, GnuTLS 2.8.5 and earlier, Mozilla Network Security Services (NSS) 3.12.4 and earlier, multiple Cisco products, and other products, does not properly associate renegotiation handshakes with an existing connection, which allows man-in-the-middle attackers to insert data into HTTPS sessions, and possibly other types of sessions protected by TLS or SSL, by sending an unauthenticated request that is processed retroactively by a server in a post-renegotiation context, related to a "plaintext injection" attack, aka the "Project Mogul" issue. |
