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CVE-2026-88648

gnutls: gnutls: Cross-domain certificate restriction bypass via incomplete X.509 validation

In GnuTLS v3.8.13, an excluded msUPN/SRV otherName is never checked. 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 · 3.7 Low EPSS < 1% KEV · Not listed
Vendors
Gnu
Products
Gnutls
CVE-2026-88647

gnutls: gnutls: Information disclosure via hostname verification bypass

GnuTLS v3.8.13 can perhaps unexpectedly trust a certificate on the basis of Common Name when Subject Alternative Name has an SRV otherName (1.3.6.1.5.5.7.8.7) whose value is an OCTET 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 · 6.5 Medium EPSS < 1% KEV · Not listed
Vendors
Gnu
Products
Gnutls
CVE-2026-67693

gnutls: gnutls: Information disclosure via contradictory Key Usage and Extended Key Usage extensions

GnuTLS v3.8.13 does not reject end-entity X.509 certificates that contain a contradictory combination of Key Usage (KU) and Extended Key Usage (EKU). 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 · 3.7 Low EPSS < 1% KEV · Not listed
Vendors
Gnu
Products
Gnutls
CVE-2026-42012

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.

CVSS 3.1 · 7.1 High EPSS < 1% KEV · Not listed
Vendors
Gnu Redhat
Products
Gnutls Cert Manager Discovery and 14 more
CVE-2023-0361

gnutls: timing side-channel in the TLS RSA key exchange code

A timing side-channel in the handling of RSA ClientKeyExchange messages was discovered in GnuTLS. This side-channel can be sufficient to recover the key encrypted in the RSA ciphertext across a network in a Bleichenbacher style attack. To achieve a successful decryption the attacker would need to send a large amount of specially crafted messages to the vulnerable server. By recovering the secret from the ClientKeyExchange message, the attacker would be able to decrypt the application data exchanged over that connection.

CVSS 3.1 · 7.4 High EPSS 1.5% KEV · Not listed
Vendors
Debian Fedoraproject Gnu and 2 more
Products
Debian Linux Fedora Gnutls and 5 more
CVE-2022-2509

gnutls: Double free during gnutls_pkcs7_verify

A vulnerability found in gnutls. This security flaw happens because of a double free error occurs during verification of pkcs7 signatures in gnutls_pkcs7_verify function.

CVSS 3.1 · 7.5 High EPSS 2.3% KEV · Not listed
Vendors
Debian Fedoraproject Gnu and 1 more
Products
Debian Linux Fedora Gnutls and 1 more
CVE-2021-4209

GnuTLS: Null pointer dereference in MD_UPDATE

A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.

CVSS 3.1 · 6.5 Medium EPSS 2.0% KEV · Not listed
Vendors
Gnu Netapp Redhat
Products
Gnutls Active Iq Unified Manager Hci Bootstrap Os and 3 more
CVE-2021-20232

gnutls: Use after free in client_send_params in lib/ext/pre_shared_key.c

A flaw was found in gnutls. A use after free issue in client_send_params in lib/ext/pre_shared_key.c may lead to memory corruption and other potential consequences.

CVSS 3.1 · 9.8 Critical EPSS 3.4% KEV · Not listed
Vendors
Fedoraproject Gnu Redhat
Products
Fedora Gnutls Enterprise Linux
CVE-2020-24659

gnutls: Heap buffer overflow in handshake with no_renegotiation alert sent

An issue was discovered in GnuTLS before 3.6.15. A server can trigger a NULL pointer dereference in a TLS 1.3 client if a no_renegotiation alert is sent with unexpected timing, and then an invalid second handshake occurs. The crash happens in the application's error handling path, where the gnutls_deinit function is called after detecting a handshake failure.

CVSS 3.1 · 7.5 High EPSS 3.8% KEV · Not listed
Vendors
Canonical Fedoraproject Gnu and 2 more
Products
Ubuntu Linux Fedora Gnutls and 2 more
CVE-2020-13777

gnutls: session resumption works without master key allowing MITM

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

CVSS 3.1 · 7.4 High EPSS 22.5% KEV · Not listed
Vendors
Canonical Debian Fedoraproject and 2 more
Products
Ubuntu Linux Debian Linux Fedora and 4 more
CVE-2020-11501

gnutls: DTLS client hello contains a random value of all zeroes

GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS. The earliest affected version is 3.6.3 (2018-07-16) because of an error in a 2017-10-06 commit. The DTLS client always uses 32 '\0' bytes instead of a random value, and thus contributes no randomness to a DTLS negotiation. This breaks the security guarantees of the DTLS protocol.

CVSS 3.1 · 7.4 High EPSS 3.4% KEV · Not listed
Vendors
Canonical Debian Fedoraproject and 3 more
Products
Ubuntu Linux Debian Linux Fedora and 3 more
CVE-2009-3555

TLS: MITM attacks via session renegotiation

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.

CVSS 3.1 · 9.8 Critical EPSS 87.3% KEV · Not listed
Vendors
Apache Canonical Debian and 6 more
Products
Http Server Ubuntu Linux Debian Linux and 12 more
CVE-2009-2730

gnutls: incorrect verification of SSL certificate with NUL in name (GNUTLS-SA-2009-4)

libgnutls in GnuTLS before 2.8.2 does not properly handle a '\0' character in a domain name in the subject's (1) Common Name (CN) or (2) Subject Alternative Name (SAN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority.

CVSS 2.0 · 7.5 High EPSS 2.2% KEV · Not listed
Vendors
Gnu Redhat
Products
Gnutls Enterprise Linux
CVE-2008-1950

GNUTLS-SA-2008-1-3 GnuTLS memory overread flaw

Integer signedness error in the _gnutls_ciphertext2compressed function in lib/gnutls_cipher.c in libgnutls in GnuTLS before 2.2.4 allows remote attackers to cause a denial of service (buffer over-read and crash) via a certain integer value in the Random field in an encrypted Client Hello message within a TLS record with an invalid Record Length, which leads to an invalid cipher padding length, aka GNUTLS-SA-2008-1-3.

CVSS 2.0 · 5.0 Medium EPSS 5.0% KEV · Not listed
Vendors
Gnu Redhat
Products
Gnutls Enterprise Linux
CVE-2009-2409

deprecate MD2 in SSL cert validation (Kaminsky)

The Network Security Services (NSS) library before 3.12.3, as used in Firefox; GnuTLS before 2.6.4 and 2.7.4; OpenSSL 0.9.8 through 0.9.8k; and other products support MD2 with X.509 certificates, which might allow remote attackers to spoof certificates by using MD2 design flaws to generate a hash collision in less than brute-force time. NOTE: the scope of this issue is currently limited because the amount of computation required is still large.

CVSS 2.0 · 5.1 Medium EPSS 4.3% KEV · Not listed
Vendors
Gnu Mozilla Openssl and 1 more
Products
Gnutls Network Security Services Openssl and 4 more
CVE-2009-1417

gnutls: certificate expiration not checked by gnutls-cli [GNUTLS-SA-2009-3]

gnutls-cli in GnuTLS before 2.6.6 does not verify the activation and expiration times of X.509 certificates, which allows remote attackers to successfully present a certificate that is (1) not yet valid or (2) no longer valid, related to lack of time checks in the _gnutls_x509_verify_certificate function in lib/x509/verify.c in libgnutls_x509, as used by (a) Exim, (b) OpenLDAP, and (c) libsoup.

CVSS 2.0 · 5.0 Medium EPSS 1.4% KEV · Not listed
Vendors
Gnu
Products
Gnutls
CVE-2008-1949

GNUTLS-SA-2008-1-2 GnuTLS null-pointer dereference

The _gnutls_recv_client_kx_message function in lib/gnutls_kx.c in libgnutls in gnutls-serv in GnuTLS before 2.2.4 continues to process Client Hello messages within a TLS message after one has already been processed, which allows remote attackers to cause a denial of service (NULL dereference and crash) via a TLS message containing multiple Client Hello messages, aka GNUTLS-SA-2008-1-2.

CVSS 2.0 · 9.3 Critical EPSS 5.8% KEV · Not listed
Vendors
Gnu Redhat
Products
Gnutls Enterprise Linux
CVE-2009-1416

gnutls: All DSA keys generated using GnuTLS 2.6.x are corrupt [GNUTLS-SA-2009-2]

lib/gnutls_pk.c in libgnutls in GnuTLS 2.5.0 through 2.6.5 generates RSA keys stored in DSA structures, instead of the intended DSA keys, which might allow remote attackers to spoof signatures on certificates or have unspecified other impact by leveraging an invalid DSA key.

CVSS 2.0 · 7.5 High EPSS 3.9% KEV · Not listed
Vendors
Gnu
Products
Gnutls
CVE-2009-1415

gnutls: Double free and free of invalid pointer on certain errors [GNUTLS-SA-2009-1]

lib/pk-libgcrypt.c in libgnutls in GnuTLS before 2.6.6 does not properly handle invalid DSA signatures, which allows remote attackers to cause a denial of service (application crash) and possibly have unspecified other impact via a malformed DSA key that triggers a (1) free of an uninitialized pointer or (2) double free.

CVSS 2.0 · 4.3 Medium EPSS 7.9% KEV · Not listed
Vendors
Gnu
Products
Gnutls