CVE-2026-9539

Name	CVE-2026-9539
Description	An out-of-bounds heap read and integer underflow in the TCP urgent data handling (sosendoob) in freedesktop.org libslirp version before v4.9.2 on hypervisor host environments (e.g., QEMU) allows a privileged guest VM attacker (root or CAP_NET_RAW) to leak gigabytes of sensitive host-process heap memory via sending crafted TCP segments with manipulated URG flags and urgent pointers (ti_urp).
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libslirp (PTS)	bullseye	4.4.0-1+deb11u2	vulnerable
	bookworm	4.7.0-1	vulnerable
	trixie	4.8.0-1	vulnerable
	forky, sid	4.9.3-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libslirp	source	(unstable)	4.9.2-1

Notes

[trixie] - libslirp <no-dsa> (Minor issue)
https://gitlab.freedesktop.org/slirp/libslirp/-/work_items/93
https://gitlab.freedesktop.org/slirp/libslirp/-/commit/927bca7344e31fd58e2f7afaca784aad4400eb84 (v4.9.2)