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7.5 High

CVE-2026-33846 Gnutls: gnutls: denial of service via heap buffer overflow in dtls handshake fragment reassembly

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.

CVSS 3.1 detail

Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitable remotely over the network, without an account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector
Network
Attack complexity
Low
Privileges required
None
Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Affected products and versions

Product Affected versions Fixed in
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published
Red Hat Hardened Images 3.8 earliest → < 3.8.13-1.hum1 3.8.13-1.hum1
Red Hat OpenShift Container Platform 4 Versions not published
Red Hat Enterprise Linux 10.0 Extended Update Support Versions not published
Red Hat Update Infrastructure 5 1787241260 earliest → < 1787241260 1787241260
Show the 49 other branches
Product Affected versions Fixed in
Red Hat Discovery 2 1782166952 earliest → < 1782166952 1782166952
Red Hat Enterprise Linux 9.6 Extended Update Support Versions not published
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Versions not published
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Versions not published
Red Hat Enterprise Linux 8.8 Telecommunications Update Service Versions not published
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Versions not published
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Versions not published
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Versions not published
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Versions not published
Red Hat Enterprise Linux AppStream EUS (v. 10.0) Versions not published
Red Hat Enterprise Linux AppStream (v. 10) Versions not published
Red Hat Enterprise Linux AppStream (v. 8) Versions not published
Red Hat Enterprise Linux AppStream AUS (v.8.4) Versions not published
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) Versions not published
Red Hat Enterprise Linux AppStream AUS (v.8.6) Versions not published
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) Versions not published
Red Hat Enterprise Linux AppStream E4S (v.8.8) Versions not published
Red Hat Enterprise Linux AppStream TUS (v.8.8) Versions not published
Red Hat Enterprise Linux AppStream E4S (v.9.4) Versions not published
Red Hat Enterprise Linux AppStream EUS (v.9.6) Versions not published
Red Hat Enterprise Linux AppStream (v. 9) Versions not published
Red Hat Enterprise Linux BaseOS EUS (v. 10.0) Versions not published
Red Hat Enterprise Linux BaseOS (v. 10) Versions not published
Red Hat Enterprise Linux BaseOS (v. 8) Versions not published
Red Hat Enterprise Linux BaseOS AUS (v.8.4) Versions not published
Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) Versions not published
Red Hat Enterprise Linux BaseOS AUS (v.8.6) Versions not published
Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) Versions not published
Red Hat Enterprise Linux BaseOS E4S (v.8.8) Versions not published
Red Hat Enterprise Linux BaseOS TUS (v.8.8) Versions not published
Red Hat Enterprise Linux BaseOS E4S (v.9.4) Versions not published
Red Hat Enterprise Linux BaseOS EUS (v.9.6) Versions not published
Red Hat Enterprise Linux BaseOS (v. 9) Versions not published
Red Hat Enterprise Linux 7 Extended Lifecycle Support Versions not published
Red Hat Enterprise Linux Server (v. 7 ELS) Versions not published
Red Hat AI Inference Server 3.2 1782951244 earliest → < 1782951244 1782951244
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Versions not published
Red Hat OpenShift Container Platform 4.18 418.94 earliest → < 418.94.202608142238-0 418.94.202608142238-0
Red Hat OpenShift Container Platform 4.19 4.19 earliest → < 4.19.9.6.202608182320-0 4.19.9.6.202608182320-0
Red Hat OpenShift Container Platform 4.14 414.92 earliest → < 414.92.202608172040-0 414.92.202608172040-0
Red Hat OpenShift Container Platform 4.15 415.92 earliest → < 415.92.202608180329-0 415.92.202608180329-0
Red Hat OpenShift Container Platform 4.16 416.94 earliest → < 416.94.202608150307-0 416.94.202608150307-0
Red Hat OpenShift Container Platform 4.12 412.86 earliest → < 412.86.202608241157-0 412.86.202608241157-0
Red Hat OpenShift Container Platform 4.17 417.94 earliest → < 417.94.202608250221-0 417.94.202608250221-0
Red Hat OpenShift Container Platform 4.13 413.92 earliest → < 413.92.202609080414-0 413.92.202609080414-0
Cert Manager support for Red Hat OpenShift release 1.20 1790598593 earliest → < 1790598593 1790598593
Red Hat OpenShift AI 3.4 1790703542 earliest → < 1790703542 1790703542
Cert Manager support for Red Hat OpenShift release 1.17 1791970484 earliest → < 1791970484 1791970484
Cert Manager support for Red Hat OpenShift release 1.18 1791966259 earliest → < 1791966259 1791966259

References

Timeline

  1. Published
  2. Last modified

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