# CVE-2026-23557: xen: Any guest can cause xenstored to crash by issuing a XS_RESET_WATCHES command within a transaction due to an assert()...

CVE-2026-23557 is fixed in xen on 1 platform, first by DEBIAN-CVE-2026-23557, released May 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-23557
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 19, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | xen Debian 12.15 (bookworm) | 4.17.7-0+deb12u1 | [DEBIAN-CVE-2026-23557](https://patchblox.com/security/data/fix/linux/debian-cve-2026-23557.md) | May 19, 2026 |
| Linux | xen Debian 13.5 (trixie) | 4.20.3+127-gc42374a105-0+deb13u1 | [DEBIAN-CVE-2026-23557](https://patchblox.com/security/data/fix/linux/debian-cve-2026-23557.md) | May 19, 2026 |
| Linux | xen Debian 14 | 4.20.3+127-gc42374a105-1 | [DEBIAN-CVE-2026-23557](https://patchblox.com/security/data/fix/linux/debian-cve-2026-23557.md) | May 19, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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