CVE-2026-23558

⚠️ high

Summary

The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.

CVSS Score

7.8

High

EPSS Score

0.0

Exploit Probability

Published Date

2026-05-19

First Seen: 2026-05-20

📊 Relative Risk Intelligence

This CVE is Moderate Risk - more severe than 69.6% of all 328,009 vulnerabilities in our database.

#99,625

Above average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: May 19, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

Requires human interaction

💥 Technical Impact

Total

Complete system compromise possible

🏆 Discovered By

This issue was discovered by Claude Opus 4.6 and diagnosed as a security issue by Rafal Wojtczuk.

SSVC data provided by CISA

Last Modified 2026-05-19

Source NVD 🔗

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

CWE IDs (Weakness Types)

CWE-362

📦 Affected Products 1

Vendor	Product	Status	Affected Versions
xen	xen	Affected	> 4.0.0

🔗 References 3

https://xenbits.xenproject.org/xsa/advisory-486.html

Mitigation Patch Vendor Advisory

http://www.openwall.com/lists/oss-security/2026/04/2...

Mailing List Mitigation Patch Third Party Advisory

http://xenbits.xen.org/xsa/advisory-486.html

Mitigation Patch Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	Summary	Published
CVE-2026-23557	🔶 medium	6.5	Any guest can cause xenstored to crash by issuing a XS_RESET_WATCHES command within a transaction due to an assert() tri...	2026-05-19
CVE-2026-23554	⚠️ high	7.8	The Intel EPT paging code uses an optimization to defer flushing of any cached EPT state until the p2m lock is dropped, ...	2026-03-23
CVE-2026-23555	⚠️ high	7.1	Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstor...	2026-03-23
CVE-2025-58150	⚠️ high	8.8	Shadow mode tracing code uses a set of per-CPU variables to avoid cumbersome parameter passing. Some of these variables...	2026-01-28
CVE-2026-23553	ℹ️ low	2.9	In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it was the pr...	2026-01-28
CVE-2025-58147	⚠️ high	7.5	[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to whi...	2025-10-31

These CVEs affect the same products