CVE-2026-42010: gnu gnutls Improper Null Termination
Vulnerability summary
CVE-2026-42010 is a critical (CVSS 9.8) Improper Null Termination vulnerability in gnu gnutls. EPSS estimates a 0.94% chance of exploitation in the next 30 days, higher than 60.3% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 14 · Related 4Timeline
- 07-05-2026PublishedVulnerability first disclosed.
- 14-10-2026Last modifiedVulnerability information updated.
Description
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 metrics
5 scores · 5 sources · 1 version- CVE.orgCNA7.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:NDiffers
- OSV · AlpineEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.94%
Chance of exploitation in the next 30 days
Percentile
60%
Versus all other CVEs
30-day change
-0.11 pp
From 1.05% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-170Improper Null TerminationThe product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
- CWE-626Null Byte Interaction Error (Poison Null Byte)The product does not properly handle null bytes or NUL characters when passing data between different representations or components.
Affected systems
Redhat3 products
- enterprise_linuxEOL6.0 | 7.0 | 8.0 | 9.0 | 10.0
- hardened_imagesna
- openshift_container_platform4.0
Alpine1 product
- gnutls< 3.8.13-r0
Debian1 product
- gnutls28< 3.7.9-2+deb12u7 | < 3.8.9-3+deb13u4 | < 3.8.13-1
Gnu1 product
- gnutlsna
Ubuntu1 product
- gnutls28< 3.6.13-2ubuntu1.12+esm2 | < 3.7.3-4ubuntu1.9 | All versions (No fix recorded) | < 3.7.3-4ubuntu1.9+Fips1 | < 3.8.3-1.1ubuntu3.6 | < 3.8.3-1.1ubuntu3.6+Fips1.2 | < 3.8.9-3ubuntu2.2 | < 3.8.12-2ubuntu1.1
5 vendors · 7 products
