VulnerabilityAwaiting Analysis

CVE-2026-33846

A heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS.

HIGH 7.5EPSS 1.26%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.26%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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: 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 1.26% probability · 68th percentile
CISA KEV: Not listed
Weakness: CWE-130
Source: secalert@redhat.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.