Libssh: invalid return code for chacha20 poly1305 with openssl backend (CVE-2025-5987)

Why this deserves its current priority

CVSS is 8.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps libssh (generic), Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:a:libssh:libssh::::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
libsshgeneric	>=0.10.0 <0.11.2	0.11.2
Red Hat/openshift/ose-rhel-coreos-8generic	*	Not reported
Red Hat/openshift/ose-rhel-coreos-9generic	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for libssh, Red Hat/openshift/ose-rhel-coreos-8, Red Hat/openshift/ose-rhel-coreos-9.
Review the reported fix. Source-reported workaround: A workaround for this issue is to disable the [email protected] cipher in applications using libssh when libssh is compiled with the OpenSSL backend, so the vulnerable ChaCha20-Poly1305 initialization path is not used. Alternatively, upgrade to a version of libssh containing the fix; upstream has released libssh 0.11.2 to correct this defect, and administrators are advised to upgrade or apply the upstream patch as soon as possible.

Evidence timeline and material changes

Published upstream
Jul 7, 2025
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jun 25, 2026

Sources and claim methodology

Upstream source description

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

Quoted source text, attributed separately from HOL analysis.

Libssh: invalid return code for chacha20 poly1305 with openssl backendCVE-2025-5987