CVE-2026-31789

NameCVE-2026-31789
DescriptionIssue summary: Converting an excessively large OCTET STRING value to a hexadecimal string leads to a heap buffer overflow on 32 bit platforms. Impact summary: A heap buffer overflow may lead to a crash or possibly an attacker controlled code execution or other undefined behavior. If an attacker can supply a crafted X.509 certificate with an excessively large OCTET STRING value in extensions such as the Subject Key Identifier (SKID) or Authority Key Identifier (AKID) which are being converted to hex, the size of the buffer needed for the result is calculated as multiplication of the input length by 3. On 32 bit platforms, this multiplication may overflow resulting in the allocation of a smaller buffer and a heap buffer overflow. Applications and services that print or log contents of untrusted X.509 certificates are vulnerable to this issue. As the certificates would have to have sizes of over 1 Gigabyte, printing or logging such certificates is a fairly unlikely operation and only 32 bit platforms are affected, this issue was assigned Low severity. The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDSA-6201-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
openssl (PTS)bullseye1.1.1w-0+deb11u1vulnerable
bullseye (security)1.1.1w-0+deb11u5vulnerable
bookworm3.0.18-1~deb12u1vulnerable
bookworm (security)3.0.19-1~deb12u2fixed
trixie3.5.5-1~deb13u1vulnerable
trixie (security)3.5.5-1~deb13u2fixed
forky, sid3.6.1-3vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
opensslsourcebookworm3.0.19-1~deb12u2DSA-6201-1
opensslsourcetrixie3.5.5-1~deb13u2DSA-6201-1
opensslsource(unstable)(unfixed)

Notes

https://openssl-library.org/news/secadv/20260407.txt

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