CVE-2026-33846

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

Published May 4, 2026 CVSS 3.1 · 7.5 High EPSS 1.3% KEV · Not listed
Description
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.

Remediation

Vendor Workaround

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4595-1 gnutls28 security update
Debian DSA Debian DSA DSA-6281-1 gnutls28 security update
Ubuntu USN Ubuntu USN USN-8284-1 GnuTLS vulnerabilities
Ubuntu USN Ubuntu USN USN-8502-1 GnuTLS vulnerabilities
References
Link Providers
https://access.redhat.com/errata/RHSA-2026:13274 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:20611 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:20612 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:20613 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:26319 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:26409 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:29197 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:30004 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:30849 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:30850 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:32962 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:33125 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:34372 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36004 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36005 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36006 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:41921 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:56786 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:56853 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:56911 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:57402 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:57483 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:58981 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:59831 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:60019 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:65839 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:72502 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:74674 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82304 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82322 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82347 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82354 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82372 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82857 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82888 cve-icon cve-icon
https://access.redhat.com/security/cve/CVE-2026-33846 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2450625 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-33846 cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33846.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-33846 cve-icon
History
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:6 cpe:/o:redhat:rhel_els:6
Type Values Removed Values Added
First Time appeared Redhat openshift Ai
CPEs cpe:/a:redhat:openshift_ai:3.4::el9
Vendors & Products Redhat openshift Ai
References
Type Values Removed Values Added
First Time appeared Redhat cert Manager
CPEs cpe:/a:redhat:cert_manager:1.20::el9
Vendors & Products Redhat cert Manager
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:openshift:4.17::el9
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:openshift:4.14::el9
cpe:/a:redhat:openshift:4.15::el9
cpe:/a:redhat:openshift:4.16::el9
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:rhel_e4s:9.2::appstream
cpe:/o:redhat:rhel_e4s:9.2::baseos
References
Type Values Removed Values Added
First Time appeared Redhat ai Inference Server
CPEs cpe:/a:redhat:ai_inference_server:3.2::el9
Vendors & Products Redhat ai Inference Server
References
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:7 cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:rhel_aus:8.4::appstream
cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
cpe:/o:redhat:rhel_aus:8.4::baseos
cpe:/o:redhat:rhel_eus_long_life:8.4::baseos
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:rhel_e4s:9.4::appstream
cpe:/o:redhat:rhel_e4s:9.4::baseos
References
Type Values Removed Values Added
First Time appeared Redhat rhel Aus
Redhat rhel E4s
Redhat rhel Eus Long Life
Redhat rhel Tus
CPEs cpe:/a:redhat:rhel_aus:8.6::appstream
cpe:/a:redhat:rhel_e4s:8.8::appstream
cpe:/a:redhat:rhel_eus_long_life:8.6::appstream
cpe:/a:redhat:rhel_tus:8.8::appstream
cpe:/o:redhat:rhel_aus:8.6::baseos
cpe:/o:redhat:rhel_e4s:8.8::baseos
cpe:/o:redhat:rhel_eus_long_life:8.6::baseos
cpe:/o:redhat:rhel_tus:8.8::baseos
Vendors & Products Redhat rhel Aus
Redhat rhel E4s
Redhat rhel Eus Long Life
Redhat rhel Tus
References
Type Values Removed Values Added
First Time appeared Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.6::appstream
cpe:/o:redhat:rhel_eus:9.6::baseos
Vendors & Products Redhat rhel Eus
References
Type Values Removed Values Added
First Time appeared Redhat discovery
CPEs cpe:/a:redhat:discovery:2::el9
Vendors & Products Redhat discovery
References
Type Values Removed Values Added
First Time appeared Redhat enterprise Linux Eus
Redhat rhui
CPEs cpe:/a:redhat:rhui:5::el9
cpe:/o:redhat:enterprise_linux_eus:10.0
Vendors & Products Redhat enterprise Linux Eus
Redhat rhui
References
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:9 cpe:/a:redhat:enterprise_linux:9::appstream
cpe:/o:redhat:enterprise_linux:9::baseos
References
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:10.2
References
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:8 cpe:/a:redhat:enterprise_linux:8::appstream
cpe:/o:redhat:enterprise_linux:8::baseos
References
Type Values Removed Values Added
First Time appeared Gnu
Gnu gnutls
Redhat hardened Images
Redhat openshift Container Platform
Vendors & Products Gnu
Gnu gnutls
Redhat hardened Images
Redhat openshift Container Platform
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Gnutls: gnutls: denial of service via heap buffer overflow in dtls handshake fragment reassembly
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat openshift
Weaknesses CWE-130
CPEs cpe:/a:redhat:hummingbird:1
cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat openshift
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}