JLSEC-2026-247 Null pointer dereference in PKCS12 parsing

Issue summary: Processing a maliciously formatted PKCS12 file may lead OpenSSL to crash leading to a potential Denial of Service attack Impact summary: Applications loading files in the PKCS12 format from untrusted sources might terminate abruptly. A file in PKCS12 format can contain certificates...

JLSEC-2026-218 In situations where an attacker receives automated notification of the success or failure of a...

In situations where an attacker receives automated notification of the success or failure of a decryption attempt an attacker, after sending a very large number of messages to be decrypted, can recover a CMS/PKCS7 transported encryption key or decrypt any RSA encrypted message that was encrypted...

JLSEC-2026-223 openssl-src NULL pointer Dereference in `signature_algorithms` processing

An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signaturealgorithms extension where it was present in the initial ClientHello, but includes a signaturealgorithmscert extension then a NU...

JLSEC-2026-240 Issue summary: The AES-SIV cipher implementation contains a bug that causes it to ignore empty...

Issue summary: The AES-SIV cipher implementation contains a bug that causes it to ignore empty associated data entries which are unauthenticated as a consequence. Impact summary: Applications that use the AES-SIV algorithm and want to authenticate empty data entries as associated data can be misl...

JLSEC-2026-244 Issue summary: Generating excessively long X9.42 DH keys or checking excessively long X9.42 DH keys...

Issue summary: Generating excessively long X9.42 DH keys or checking excessively long X9.42 DH keys or parameters may be very slow. Impact summary: Applications that use the functions DHgeneratekey to generate an X9.42 DH key may experience long delays. Likewise, applications that use...

JLSEC-2026-246 Issue summary: Checking excessively long invalid RSA public keys may take a long time.

Issue summary: Checking excessively long invalid RSA public keys may take a long time. Impact summary: Applications that use the function EVPPKEYpubliccheck to check RSA public keys may experience long delays. Where the key that is being checked has been obtained from an untrusted source this may...

JLSEC-2026-235 A security vulnerability has been identified in all supported versions

A security vulnerability has been identified in all supported versions of OpenSSL related to the verification of X.509 certificate chains that include policy constraints. Attackers may be able to exploit this vulnerability by creating a malicious certificate chain that triggers exponential use of...

JLSEC-2026-219 Null pointer deference in openssl-src

Server or client applications that call the SSLcheckchain function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signaturealgorithmscert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm i...

JLSEC-2026-251 Issue summary: Calling the OpenSSL API function `SSL_free_buffers` may cause memory to be accessed...

Issue summary: Calling the OpenSSL API function SSLfreebuffers may cause memory to be accessed that was previously freed in some situations Impact summary: A use after free can have a range of potential consequences such as the corruption of valid data, crashes or execution of arbitrary code...

JLSEC-2026-258 Issue summary: The 'openssl dgst' command-line tool silently truncates input data to 16MB when using...

Issue summary: The 'openssl dgst' command-line tool silently truncates input data to 16MB when using one-shot signing algorithms and reports success instead of an error. Impact summary: A user signing or verifying files larger than 16MB with one-shot algorithms such as Ed25519, Ed448, or ML-DSA m...

JLSEC-2026-259 Issue summary: Use of -addreject option with the openssl x509 application adds a trusted use instead...

Issue summary: Use of -addreject option with the openssl x509 application adds a trusted use instead of a rejected use for a certificate. Impact summary: If a user intends to make a trusted certificate rejected for a particular use it will be instead marked as trusted for that use. A copy & paste...

JLSEC-2026-264 Issue summary: A type confusion vulnerability exists in the TimeStamp Response verification code...

Issue summary: A type confusion vulnerability exists in the TimeStamp Response verification code where an ASN1TYPE union member is accessed without first validating the type, causing an invalid or NULL pointer dereference when processing a malformed TimeStamp Response file. Impact summary: An...

JLSEC-2026-228 The `c_rehash` script does not properly sanitise shell metacharacters to prevent command injection

The crehash 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...

JLSEC-2026-256 Issue summary: Parsing CMS AuthEnvelopedData message with maliciously crafted AEAD parameters can...

Issue summary: Parsing CMS AuthEnvelopedData or EnvelopedData message with maliciously crafted AEAD parameters can trigger a stack buffer overflow. Impact summary: A stack buffer overflow may lead to a crash, causing Denial of Service, or potentially remote code execution. When parsing CMS...

JLSEC-2026-239 Issue summary: Processing some specially crafted ASN.1 object identifiers or data containing them...

Issue summary: Processing some specially crafted ASN.1 object identifiers or data containing them may be very slow. Impact summary: Applications that use OBJobj2txt directly, or use any of the OpenSSL subsystems OCSP, PKCS7/SMIME, CMS, CMP/CRMF or TS with no message size limit may experience...

JLSEC-2026-236 Applications that use a non-default option when verifying certificates may be vulnerable to an...

Applications that use a non-default option when verifying certificates may be vulnerable to an attack from a malicious CA to circumvent certain checks. Invalid certificate policies in leaf certificates are silently ignored by OpenSSL and other certificate policy checks are skipped for that...

JLSEC-2026-231 openssl-src subject to Timing Oracle in RSA Decryption

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 fo...

JLSEC-2026-220 The X.509 GeneralName type is a generic type for representing different types of names

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 GENERALNAMEcmp which compares different instances of a GENERALNAME to see if they are equal or not. This function behaves incorrect...

JLSEC-2026-261 Issue summary: Writing large, newline-free data into a BIO chain using the line-buffering filter...

Issue summary: Writing large, newline-free data into a BIO chain using the line-buffering filter where the next BIO performs short writes can trigger a heap-based out-of-bounds write. Impact summary: This out-of-bounds write can cause memory corruption which typically results in a crash, leading ...

JLSEC-2026-227 openssl-src's infinite loop in `BN_mod_sqrt()` reachable when parsing certificates

The BNmodsqrt function, which computes a modular square root, contains a bug that can cause it to loop forever for non-prime moduli. Internally this function is used when parsing certificates that contain elliptic curve public keys in compressed form or explicit elliptic curve parameters with a...