CVE-2026-9539libslirp TCP URG OOB Read Information Leak
- 6.5MediumCVSS base score
- 0.22%Exploitation in 30 daysEPSS · top 87% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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).
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.
Show the exploits1
References tagged exploit1 reference
- https://gitlab.freedesktop.org/slirp/libslirp/-/work_items/93 (opens in a new tab)issue-trackingexploit
Timeline
ID reserved
By STAR_Labs
- 29 days later
· 29 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| STAR_LabsCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
| NVDNVD · Awaiting Analysis | 3.1 | Medium6.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.22% · top 87% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Affected products
- affected < 4.9.2
References
References3
- https://gitlab.freedesktop.org/slirp/libslirp/-/work_items/93 (opens in a new tab)issue-trackingexploit
- https://gitlab.freedesktop.org/slirp/libslirp/-/commit/927bca7344e31fd58e2f7afaca784aad4400eb84 (opens in a new tab)patch
- https://gitlab.freedesktop.org/slirp/libslirp/-/releases/v4.9.2 (opens in a new tab)release-notes
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-38654 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-9539)Record last updated .