CVE-2026-42013

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.

CVSS 3.1 · 8.2 High EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Cert Manager Discovery and 14 more

CVE-2026-5419

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.

CVSS 3.1 · 3.7 Low EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Cert Manager Discovery and 11 more

CVE-2026-3832

Gnutls: gnutls: security bypass allows acceptance of revoked server certificates via crafted ocsp response

A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted Online Certificate Status Protocol (OCSP) response during a TLS handshake. Due to a logic error in how gnutls processes multi-record OCSP responses, a client with OCSP verification enabled may incorrectly accept a revoked server certificate, potentially leading to a compromise of trust.

CVSS 3.1 · 3.7 Low EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Cert Manager Discovery and 8 more

CVE-2026-42014

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.

CVSS 3.1 · 6.6 Medium EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Cert Manager Discovery and 14 more

CVE-2026-3833

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.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Cert Manager Discovery and 14 more

CVE-2026-5260

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.

CVSS 3.1 · 8.2 High EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Cert Manager Discovery and 14 more

CVE-2025-32990

Gnutls: vulnerability in gnutls certtool template parsing

A heap-buffer-overflow (off-by-one) flaw was found in the GnuTLS software in the template parsing logic within the certtool utility. When it reads certain settings from a template file, it allows an attacker to cause an out-of-bounds (OOB) NULL pointer write, resulting in memory corruption and a denial-of-service (DoS) that could potentially crash the system.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ceph Storage Discovery and 8 more

CVE-2025-32989

Gnutls: vulnerability in gnutls sct extension parsing

A heap-buffer-overread vulnerability was found in GnuTLS in how it handles the Certificate Transparency (CT) Signed Certificate Timestamp (SCT) extension during X.509 certificate parsing. This flaw allows a malicious user to create a certificate containing a malformed SCT extension (OID 1.3.6.1.4.1.11129.2.4.2) that contains sensitive data. This issue leads to the exposure of confidential information when GnuTLS verifies certificates from certain websites when the certificate (SCT) is not checked correctly.

CVSS 3.1 · 5.3 Medium EPSS 1.5% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ceph Storage Discovery and 8 more

CVE-2025-32988

Gnutls: vulnerability in gnutls othername san export

A flaw was found in GnuTLS. A double-free vulnerability exists in GnuTLS due to incorrect ownership handling in the export logic of Subject Alternative Name (SAN) entries containing an otherName. If the type-id OID is invalid or malformed, GnuTLS will call asn1_delete_structure() on an ASN.1 node it does not own, leading to a double-free condition when the parent function or caller later attempts to free the same structure. This vulnerability can be triggered using only public GnuTLS APIs and may result in denial of service or memory corruption, depending on allocator behavior.

CVSS 3.1 · 6.5 Medium EPSS 1.5% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ceph Storage Discovery and 8 more

CVE-2024-0567

Gnutls: rejects certificate chain with distributed trust

A vulnerability was found in GnuTLS, where a cockpit (which uses gnuTLS) rejects a certificate chain with distributed trust. This issue occurs when validating a certificate chain with cockpit-certificate-ensure. This flaw allows an unauthenticated, remote client or attacker to initiate a denial of service attack.

CVSS 3.1 · 7.5 High EPSS 1.4% KEV · Not listed

Vendors

Debian Fedoraproject Gnu and 2 more

Products

Debian Linux Fedora Gnutls and 7 more

CVE-2024-0553

Gnutls: incomplete fix for cve-2023-5981

A vulnerability was found in GnuTLS. The response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from the response times of ciphertexts with correct PKCS#1 v1.5 padding. This issue may allow a remote attacker to perform a timing side-channel attack in the RSA-PSK key exchange, potentially leading to the leakage of sensitive data. CVE-2024-0553 is designated as an incomplete resolution for CVE-2023-5981.

CVSS 3.1 · 7.5 High EPSS 1.6% KEV · Not listed

Vendors

Fedoraproject Gnu Redhat

Products

Fedora Gnutls Enterprise Linux and 4 more

CVE-2023-5981

Gnutls: timing side-channel in the rsa-psk authentication

A vulnerability was found that the response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from response times of ciphertexts with correct PKCS#1 v1.5 padding.

CVSS 3.1 · 5.9 Medium EPSS 1.3% KEV · Not listed

Vendors

Debian Fedoraproject Gnu and 1 more

Products

Debian Linux Fedora Gnutls and 6 more

CVE-2026-42010

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.

CVSS 3.1 · 7.1 High EPSS 1.1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ai Inference Server Cert Manager and 15 more

CVE-2026-42009

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.

CVSS 3.1 · 7.5 High EPSS 1.3% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ai Inference Server Cert Manager and 25 more

CVE-2026-33846

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 does not enforce proper bounds checking against the allocated buffer size, this results in an out-of-bounds write on the heap. The vulnerability is remotely exploitable without authentication via the DTLS handshake path and can lead to application crashes or potential memory corruption.

CVSS 3.1 · 7.5 High EPSS 1.3% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ai Inference Server Cert Manager and 15 more

CVE-2026-33845

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.

CVSS 3.1 · 7.5 High EPSS 2.1% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Ai Inference Server Cert Manager and 15 more

CVE-2026-1584

Gnutls: gnutls: remote denial of service via crafted clienthello with invalid psk binder

A flaw was found in gnutls. A remote, unauthenticated attacker can exploit this vulnerability by sending a specially crafted ClientHello message with an invalid Pre-Shared Key (PSK) binder value during the TLS handshake. This can lead to a NULL pointer dereference, causing the server to crash and resulting in a remote Denial of Service (DoS) condition.

CVSS 3.1 · 7.5 High EPSS 1.4% KEV · Not listed

Vendors

Gnu Redhat

Products

Gnutls Enterprise Linux Hardened Images and 3 more

CVE-2026-95210

gnutls: gnutls: certificates with invalid extensions incorrectly accepted

GnuTLS v3.8.13 does not reject a critical keyUsage extension when it cannot be processed, such as when extnValue is an ASN.1 NULL (05 00) instead of a BIT STRING. NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.

CVSS 3.1 · 4.8 Medium EPSS < 1% KEV · Not listed

Vendors

Gnu

Products

Gnutls

CVE-2026-95209

gnutls: gnutls: legitimate CA certificates incorrectly rejected causing denial of service

** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: none. Reason: This candidate was withdrawn by its CNA. Further investigation showed that it was not a security issue. Notes: none.

CVSS n/a EPSS n/a KEV · Not listed

Vendors

Gnu

Products

Gnutls

CVE-2026-95184

gnutls: gnutls: legitimate user certificates incorrectly rejected causing denial of service

GnuTLS v3.8.13 does not properly enforce name constraints, as demonstrated by a permitted subtree violation for "EE O=Evil accepted although outside permitted O=Good." NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.

CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

Vendors

Gnu

Products

Gnutls