CVE-2026-9539
libslirp TCP URG OOB Read Information Leak
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).
INFO
Published Date :
June 24, 2026, 5:17 a.m.
Last Modified :
June 25, 2026, 7:26 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-9539
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | b1571b85-cbc9-431f-830b-0c8155323a69 | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update libslirp to v4.9.2 or later.
- Apply vendor-provided patches for libslirp.
- Limit guest VM network privileges if possible.
Public PoC/Exploit Available at Github
CVE-2026-9539 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-9539.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-9539 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-9539
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-9539 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-9539 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 24, 2026
Action Type Old Value New Value Added Reference https://gitlab.freedesktop.org/slirp/libslirp/-/work_items/93 Added SSVC {'id': 'CVE-2026-9539', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-24T12:39:41.276722Z'} -
New CVE Received by [email protected]
Jun. 24, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://gitlab.freedesktop.org/slirp/libslirp/', 'vendor': 'freedesktop.org', 'product': 'libslirp', 'versions': [{'status': 'affected', 'changes': [{'at': '4.9.2', 'status': 'unaffected'}], 'version': '0', 'lessThan': '4.9.2', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added 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). Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N Added CWE CWE-125 Added Reference https://gitlab.freedesktop.org/slirp/libslirp/-/commit/927bca7344e31fd58e2f7afaca784aad4400eb84 Added Reference https://gitlab.freedesktop.org/slirp/libslirp/-/releases/v4.9.2 Added Reference https://gitlab.freedesktop.org/slirp/libslirp/-/work_items/93