# CVE-2026-120830: Libslirp: libslirp: out-of-bounds heap read in icmp_forward_error() leading to information disclosure

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

## Remediation

- workaround: Red Hat is not aware of a practical temporary workaround that fully mitigates this issue or meets Red Hat Product Security's standards for usability, deployment, applicability, or stability. Customers are advised to apply the relevant security updates when/if they become available. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (libslirp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (container-tools:rhel8/libslirp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (libslirp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (libslirp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.4 (high); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2026-120830 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2565424 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://gitlab.freedesktop.org/slirp/libslirp/-/commit/21b33a6c5588af9f58d15e528fdc1019452708e4 (CNA: redhat)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-120830; retrieved 2026-11-03; source updated 2026-11-03

Revision: 9878de9abf17b4c06e8b64bfc628424bbce051ecdacf6d6a4b019a05d80dff73

Canonical: https://y2.dev/cve/CVE-2026-120830

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