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OpenAdvisories
High · 8.8 CVE-2026-6679 EUVD-2026-39557GHSA-c9q2-5c67-xg9p

DTLS 1.3 ACK serialization heap buffer overflow via integer truncation

Published Jun 25, 2026 · Updated Jun 26, 2026 · Assigned by wolfSSL

Description

A heap buffer overflow could occur in the DTLS 1.3 ACK serialization path before the connecting peer is authenticated. The buffer overflow was due to an integer truncation when computing the length of the ACK record-number list, causing an undersized buffer to be allocated and then overrun. This affects builds using DTLS 1.3 and wolfSSL version 5.9.0 and earlier. A fix was added to the 5.9.1 release.

Affected products

VendorProductAffectedFixed
wolfSSL wolfSSL 5.4.0 – ≤ 5.9.0 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 13 wolfssl No fix yet —
Debian 12 wolfssl No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 25.10 wolfssl No fix yet —
Ubuntu 24.04 LTS wolfssl No fix yet —
Ubuntu 22.04 LTS wolfssl No fix yet —
Ubuntu 20.04 LTS wolfssl No fix yet —
Ubuntu 18.04 LTS wolfssl No fix yet —
Show 1 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 16.04 LTS wolfssl No fix yet —
ReleasePackageFixed inAdvisory
Alpine v3.24 wolfssl 5.9.2-r0 —

References