CVE-2026-23557

The Xen hypervisor is vulnerable to a Denial of Service (DoS) attack where any guest can cause xenstored to crash. The root cause is an assert() triggering when processing the XS_RESET_WATCHES command within a transaction. This issue does not affect builds where NDEBUG is defined. Remediation inc...

Security update for xen

This update for xen fixes the following issues: CVE-2025-54505: Floating Point Divider State Sampling on AMD CPUs AMD-SN-7053 bsc1262428. CVE-2026-23557: Xenstored DoS via XSRESETWATCHES command bsc1262178. CVE-2026-23558: grant table v2 race in status page mapping bsc1262180. Special Instruction...

Xenstored DoS via XS_RESET_WATCHES command

ISSUE DESCRIPTION Any guest can cause xenstored to crash by issuing a XSRESETWATCHES 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...