CVE-2026-23557

🔶 medium

Summary

Any guest can cause xenstored to crash by issuing a XS_RESET_WATCHES command within a transaction due to an assert() triggering. In case xenstored was built with NDEBUG #defined nothing bad will happen, as assert() is doing nothing in this case. Note that the default is not to define NDEBUG for xenstored builds even in release builds of Xen.

CVSS Score

6.5

Medium

EPSS Score

Published Date

2026-05-19

First Seen: 2026-05-20

📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 47.8% of all 321,566 vulnerabilities in our database.

#167,705

Below average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: May 19, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

Requires human interaction

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

This issue was discovered by Andrii Sultanov of Vates.

SSVC data provided by CISA

Last Modified 2026-05-19

Source NVD 🔗

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

CWE IDs (Weakness Types)

CWE-617

📦 Affected Products 1

Vendor	Product	Status	Affected Versions
xen	xen	Affected	> 4.2.0

🔗 References 3

https://xenbits.xenproject.org/xsa/advisory-484.html

Patch Vendor Advisory

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

Mailing List Patch Third Party Advisory

http://xenbits.xen.org/xsa/advisory-484.html

Patch Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-23558	⚠️ high	7.8	-	The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or ...	2026-05-19
CVE-2026-23554	⚠️ high	7.8	0.0	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	0.0	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	0.0	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	0.0	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	0.0	[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