CVE-2025-9820
published 2026-01-26CVE-2025-9820: A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label…
PriorityP417medium4CVSS 3.1
AVLACLPRNUINSUCNINAL
EPSS
0.20%
10.4th percentile
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | gnutls28 | < gnutls28 3.7.9-2+deb12u6 (bookworm) | gnutls28 3.7.9-2+deb12u6 (bookworm) |
| ubuntu | gnutls28 | — | — |
CVSS provenance
nvdv3.14.0MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
osv5.3MEDIUM
vendor_ubuntu7.5HIGH
vendor_debian4.0MEDIUM
vendor_redhat4.0MEDIUM
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OSV
gnutls28 vulnerabilities
osv·2026-02-16·CVSS 5.3
CVE-2025-14831 [MEDIUM] gnutls28 vulnerabilities
gnutls28 vulnerabilities
Tim Scheckenbach discovered that GnuTLS incorrectly handled malicious
certificates containing a large number of name constraints and subject
alternative names. A remote attacker could possibly use this issue to
cause GnuTLS to consume resources, resulting in a denial of service.
(CVE-2025-14831)
Luigino Camastra discovered that GnuTLS incorrectly handled certain PKCS11
token labels. A remote attacker could use this issue to cause GnuTLS to
crash, resulting in a denial of service, or possibly execute arbitrary
code. The default compiler options for affected releases should reduce the
vulnerability to a denial of service. (CVE-2025-9820)
GHSA
GHSA-337w-h8w7-m899: A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization
ghsa_unreviewed·2026-01-26
CVE-2025-9820 [MEDIUM] CWE-121 GHSA-337w-h8w7-m899: A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
OSV
CVE-2025-9820: A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization
osv·2026-01-26·CVSS 4.0
CVE-2025-9820 [MEDIUM] CVE-2025-9820: A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
Ubuntu
GnuTLS vulnerabilities
vendor_ubuntu·2026-07-06·CVSS 7.5
CVE-2026-33846 [HIGH] GnuTLS vulnerabilities
Title: GnuTLS vulnerabilities
Summary: Several security issues were fixed in GnuTLS.
It was discovered that GnuTLS had a timing side-channel when processing
malformed ciphertexts in RSA-PSK ClientKeyExchange. A remote attacker
could possibly use this issue to recover sensitive information. This
issue only affected Ubuntu 18.04 LTS. (CVE-2024-0553)
Bing Shi discovered that GnuTLS incorrectly handled decoding certain
DER-encoded certificates. A remote attacker could possibly use this
issue to cause GnuTLS to consume resources, leading to a denial of
service. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-12243)
Luigino Camastra discovered that GnuTLS incorrectly handled certain
PKCS11 token labels. A remote attacker could use this issue to cause
GnuTLS to crash, resulting in a deni
Ubuntu
GnuTLS vulnerabilities
vendor_ubuntu·2026-02-16·CVSS 5.3
CVE-2025-14831 [MEDIUM] GnuTLS vulnerabilities
Title: GnuTLS vulnerabilities
Summary: Several security issues were fixed in GnuTLS.
Tim Scheckenbach discovered that GnuTLS incorrectly handled malicious
certificates containing a large number of name constraints and subject
alternative names. A remote attacker could possibly use this issue to
cause GnuTLS to consume resources, resulting in a denial of service.
(CVE-2025-14831)
Luigino Camastra discovered that GnuTLS incorrectly handled certain PKCS11
token labels. A remote attacker could use this issue to cause GnuTLS to
crash, resulting in a denial of service, or possibly execute arbitrary
code. The default compiler options for affected releases should reduce the
vulnerability to a denial of service. (CVE-2025-9820)
Instructions: In general, a standard system update will make all th
Red Hat
gnutls: Stack-based Buffer Overflow in gnutls_pkcs11_token_init() Function
vendor_redhat·2025-11-18·CVSS 4.0
CVE-2025-9820 [MEDIUM] CWE-121 gnutls: Stack-based Buffer Overflow in gnutls_pkcs11_token_init() Function
gnutls: Stack-based Buffer Overflow in gnutls_pkcs11_token_init() Function
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the func
Debian
CVE-2025-9820: gnutls28 - A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_...
vendor_debian·2025·CVSS 4.0
CVE-2025-9820 [MEDIUM] CVE-2025-9820: gnutls28 - A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_...
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
Scope: local
bookworm: resolved (fixed in 3.7.9-2+deb12u6)
bullseye: resolved (fixed in 3.7.1-5+deb11u9)
forky: resolved (fixed in 3.8.11-3)
sid: resolved (fixed in 3.8.11-3)
trixie: resolved (fixed in 3.8.9-3+deb13u1)
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2025-9820 gnutls: Stack-based Buffer Overflow in gnutls_pkcs11_token_init() Function
bugzilla·2025-09-02·CVSS 4.0
CVE-2025-9820 [MEDIUM] CVE-2025-9820 gnutls: Stack-based Buffer Overflow in gnutls_pkcs11_token_init() Function
CVE-2025-9820 gnutls: Stack-based Buffer Overflow in gnutls_pkcs11_token_init() Function
Stack-based buffer overflow vulnerability in the PKCS#11 token initialization function gnutls_pkcs11_token_init() of the GnuTLS library. The flaw is caused by an unsafe memcpy into a fixed-size stack buffer (flabel[32]) without proper bounds checking. If an attacker provides a token label longer than 32 bytes, it leads to out-of-bounds memory writes, causing a crash or, in some environments, potential code execution. Although the vulnerability requires local access or interaction with a malicious PKCS#11 token, it poses a security risk by enabling denial-of-service or possible privilege escalation in applications relying on GnuTLS.
Discussion:
This issue has been addressed in the following products:
Wiz
CVE-2025-14831 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2025-14831 [HIGH] CVE-2025-14831 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2025-14831 :
GnuTLS vulnerability analysis and mitigation
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).
Source : NVD
## 5.3
Score
Published February 9, 2026
Severity MEDIUM
CNA Score 5.3
Affected Technologies
GnuTLS
Alma Linux
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 19.8
Exploitation Probability (EPSS) 0.1
Affected packages and libraries
libgnutls30-32bit
gnutls-guile
Sources
NVD
AlmaLinux 8 Severity MEDIUM Has Fix Added at: Mar 29, 2026
Wiz
CVE-2025-9820 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 4.0
CVE-2025-9820 [MEDIUM] CVE-2025-9820 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2025-9820 :
GnuTLS vulnerability analysis and mitigation
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
Source : NVD
## 4
Score
Published January 26, 2026
Severity MEDIUM
CNA Score 4.0
Affected Technologies
GnuTLS
Alma Linux
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA
Wiz
CVE-2026-1584 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-1584 [HIGH] CVE-2026-1584 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-1584 :
GnuTLS vulnerability analysis and mitigation
A TLS 1.3 resumption attempt with an invalid PSK binder value in ClientHello could lead to a denial of service attack via crashing the server.
Source : NVD
Published February 10, 2026
CNA Score N/A
Affected Technologies
GnuTLS
Linux Debian
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) N/A
Exploitation Probability (EPSS) N/A
Affected packages and libraries
gnutls-c++-debuginfo
gnutls-dane-debuginfo
Sources
NVD
Alpine 3.20, 3.21, 3.22, 3.23 Has Fix Added at: Feb 24, 2026
Alpine edge Has Fix Added at: Feb 11, 2026
Debian 14 Has Fix Added at: Feb 10, 2026
Debian Has Fix Added at: Feb 11, 2026
## Get a CVE risk assess
https://access.redhat.com/errata/RHSA-2026:13812https://access.redhat.com/errata/RHSA-2026:3477https://access.redhat.com/errata/RHSA-2026:4188https://access.redhat.com/errata/RHSA-2026:4655https://access.redhat.com/errata/RHSA-2026:4943https://access.redhat.com/errata/RHSA-2026:5585https://access.redhat.com/errata/RHSA-2026:5606https://access.redhat.com/errata/RHSA-2026:7329https://access.redhat.com/errata/RHSA-2026:7477https://access.redhat.com/security/cve/CVE-2025-9820https://bugzilla.redhat.com/show_bug.cgi?id=2392528https://gitlab.com/gnutls/gnutls/-/commit/1d56f96f6ab5034d677136b9d50b5a75dff0faf5https://gitlab.com/gnutls/gnutls/-/issues/1732https://www.gnutls.org/security-new.html#GNUTLS-SA-2025-11-18http://www.openwall.com/lists/oss-security/2025/11/20/2https://cert-portal.siemens.com/productcert/html/ssa-032379.html
2026-01-26
Published