gnutls28 vulnerabilities

CVE-2026-95210

Improper certificate validation in gnutls v3.8.13 causes the application to accept certificates containing invalid extensions.

CVE-2026-95209

An issue in gnutls v3.8.13 causes legitimate CA certificates to be rejected, leading to a Denial of Service (DoS).

CVE-2026-95184

Improper certificate validation in gnutls v3.8.13 causes the application to reject legitimate certificates for valid users, leading to a Denial of Service (DoS).

CVE-2026-88648

Incomplete X.509 implementation in GnuTLS v3.8.13 allows attackers controlling a subordinate Certificate Authority to bypass cross-domain PKI restrictions and issue unauthorized certificates.

CVE-2026-88647

A hostname verification bypass in GnuTLS v3.8.13 allows attackers to circumvent the Common Name fallback mechanism and eavesdrop on communications via a crafted certificate.

CVE-2026-67693

An issue in gnutls v.3.8.13 allows an attacker to obtain sensitive information via failing to reject end-entity X.509 certificates that contain a contradictory combination of Key Usage (KU) and Extended Key Usage (EKU)

Gnutls: gnutls: use-after-free in gnutls_pkcs11_token_set_pin

A flaw was found in GnuTLS. The `gnutls_pkcs11_token_set_pin` function, used for changing the Security Officer PIN, can lead to a use-after-free vulnerability. This occurs when an attacker attempts to change the PIN with a NULL old PIN for a token that lacks a protected authentication path.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: information disclosure via timing side-channel in pkcs#7 padding removal

A flaw was found in gnutls. The PKCS#7 padding check, performed during decryption, was not constant-time. This timing side-channel could allow a remote attacker to potentially leak sensitive information about the padding bytes through observable timing differences. This vulnerability is a form of information disclosure.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: memory corruption due to off-by-one error in pkcs#12 bag handling

A flaw was found in gnutls. An off-by-one error exists in the PKCS#12 bag element bounds check. This vulnerability allows an remote attacker to write past the internal array of a PKCS#12 bag when appending to a bag that already contains 32 elements. This memory corruption could lead to a denial of service (DoS) or potentially other unspecified impacts.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: certificate validation bypass due to oversized subject alternative name

A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: certificate validation bypass due to improper handling of uri and srv sans

A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted certificate that contains Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative Names (SANs). This could cause the certificate validation process to incorrectly fall back to checking DNS hostnames against the Common Name (CN), potentially allowing the attacker to spoof legitimate services or intercept sensitive information.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: information disclosure via heap overread in rsa key exchange

A flaw was found in libgnutls. A remote attacker, by sending an extremely short premaster secret during an RSA key exchange to a server using an RSA key backed by a PKCS#11 token, could trigger a short heap overread. This memory corruption vulnerability could lead to information disclosure.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: denial of service via dtls packet reordering vulnerability

A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to unstable packet ordering or undefined behavior, resulting in a denial of service.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: security bypass due to incorrect name constraint handling

A flaw was found in gnutls. This vulnerability occurs because permitted name constraints were incorrectly ignored when previous Certificate Authorities (CAs) only had excluded name constraints. A remote attacker could exploit this to bypass critical name constraint checks during certificate validation. This bypass could lead to the acceptance of invalid certificates, potentially enabling spoofing or man-in-the-middle attacks against affected systems.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: authentication bypass via nul character in username

A flaw was found in gnutls. Servers configured with RSA-PSK (Rivest–Shamir–Adleman – Pre-Shared Key) wrongfully matched usernames containing a NUL character with truncated usernames. A remote attacker could exploit this by sending a specially crafted username, leading to an authentication bypass. This vulnerability allows an attacker to gain unauthorized access by circumventing the authentication process.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: denial of service via heap buffer overflow in dtls handshake fragment reassembly

A heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS. The issue arises in merge_handshake_packet() where incoming handshake fragments are matched and merged based solely on handshake type, without validating that the message_length field remains consistent across all fragments of the same logical message. An attacker can exploit this by sending crafted DTLS fragments with conflicting message_length values, causing the implementation to allocate a buffer based on a smaller initial fragment and subsequently write beyond its bounds using larger, inconsistent fragments. Because the merge operation

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: denial of service via dtls zero-length fragment

A flaw in GnuTLS DTLS handshake parsing allows malformed fragments with zero length and non-zero offset, leading to an integer underflow during reassembly and resulting in an out-of-bounds read. This issue is remotely exploitable and may cause information disclosure or denial of service.

• Update to 3.7.9-2+deb12u7

Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison

A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.

• Update to 3.7.9-2+deb12u7

gnutls28 - security update

gnutls28 - security update

• Update to 3.7.9-2+deb12u6

Gnutls: gnutls: denial of service via excessive resource consumption during certificate verification

A flaw was found in GnuTLS. This vulnerability allows a denial of service (DoS) by excessive CPU (Central Processing Unit) and memory consumption via specially crafted malicious certificates containing a large number of name constraints and subject alternative names (SANs).

• Update to 3.7.9-2+deb12u6