CVE-2026-79603 (CVSS 4.3)

Description

x86 PV guests can free memory pages while still keeping a stale TLB entry pointing to them. A TLB flush is only issued by Xen (if needed) when the page is re-used. Since it's possible for the page to be scrubbed ahead of the TLB flush, there's a window where a PV guest can modify an already scrubbed page.

Is your site exposed to CVE-2026-79603?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-664 CWE-664

References

Other References

https://xenbits.xenproject.org/xsa/advisory-511.html http://www.openwall.com/lists/oss-security/2026/09/08/8 http://xenbits.xen.org/xsa/advisory-511.html

Frequently Asked Questions

What is CVE-2026-79603? +

x86 PV guests can free memory pages while still keeping a stale TLB entry pointing to them. A TLB flush is only issued by Xen (if needed) when the page is re-used. Since it's possible for the page to be scrubbed ahead of the TLB flush, there's a window where a PV guest can modify an already scrubbed page. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-79603? +

CVE-2026-79603 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-79603? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-34226

OpenPLC Runtime v3 contains an input validation flaw in the /upload-program-action endpoint: the epoch_time field supplied during program uploads is …

CVE-2026-54251

netty-incubator-codec-ohttp implements Oblivious HTTP (OHTTP) gateway and client functionality using Netty. Prior to 0.0.23.Final, the OHTTP gateway decryption path in …

CVE-2026-20353 9.8

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Email Gateway and Cisco Secure …

CVE-2026-20336 8.8

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Adaptive Security Appliance Software, Cisco …

CVE-2026-8517 8.8

Object lifecycle issue in WebShare in Google Chrome on Mac prior to 148.0.7778.168 allowed a remote attacker who convinced a …

CVE-2026-20269 8.6

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software engineering team has …

CVE-2026-79603