Low · CVSS 3.5CVE-2026-115449

Libslirp: libslirp: icmp echo reply length desynchronization leaks host ip to guestCVE-2026-115449

Answer in brief

CVE-2026-115449 records a Low severity (CVSS 3.5) vulnerability in Libslirp: libslirp: icmp echo reply length desynchronization leaks host ip to guest. The current sources do not mark it as known exploited. The current feed maps Red Hat/container-tools:rhel8/libslirp (generic), Red Hat/libslirp (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 22, 2026Updated Oct 22, 2026Source checked Oct 22, 2026First seen by HOL Oct 22, 2026Material review Oct 22, 2026

Upstream Advisory

Key facts

Risk: Low · CVSS 3.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 3.5. 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 Red Hat/container-tools:rhel8/libslirp (generic), Red Hat/libslirp (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Red Hat/container-tools:rhel8/libslirpgeneric	*	Not reported
Red Hat/libslirpgeneric	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/container-tools:rhel8/libslirp, Red Hat/libslirp.
Review the reported fix. Source-reported workaround: Ensure that the QEMU process user's GID is included in the system's ping_group_range (sysctl net.ipv4.ping_group_range), which allows the SOCK_DGRAM ICMP socket path and avoids the vulnerable raw socket fallback. Alternatively, use --net none or virtio-net with a TAP backend instead of user-mode (slirp) networking.

Evidence timeline and material changes

Published upstream
Oct 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 22, 2026

Sources and claim methodology

Upstream source description

A flaw was found in libslirp. When handling ICMP echo requests, the reply length is not updated to match the actual data received from the host. Under specific conditions where the normal ICMP socket is unavailable, this length mismatch causes the host's real IP address to be leaked to the guest in the echo reply, breaking the NAT isolation that user-mode networking is expected to provide.

Quoted source text, attributed separately from HOL analysis.

Affected scope and exposure questions

The current feed maps Red Hat/container-tools:rhel8/libslirp (generic), Red Hat/libslirp (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Red Hat/container-tools:rhel8/libslirpgeneric	*	Not reported
Red Hat/libslirpgeneric	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/container-tools:rhel8/libslirp, Red Hat/libslirp.

Review the reported fix. Source-reported workaround: Ensure that the QEMU process user's GID is included in the system's ping_group_range (sysctl net.ipv4.ping_group_range), which allows the SOCK_DGRAM ICMP socket path and avoids the vulnerable raw socket fallback. Alternatively, use --net none or virtio-net with a TAP backend instead of user-mode (slirp) networking.

Sources and claim methodology

Upstream source description

Quoted source text, attributed separately from HOL analysis.