CVE-2026-120830

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.

CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

• https://access.redhat.com/security/cve/CVE-2026-120830
• https://bugzilla.redhat.com/show_bug.cgi?id=2565424
• https://gitlab.freedesktop.org/slirp/libslirp/-/commit/21b33a6c5588af9f58d15e528fdc1019452708e4