Medium severity · published May 19, 2026
CVE-2026-23557
Xenstored DoS via XS_RESET_WATCHES command
6.5
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 5% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
XE
Xen · Xen
4.2.0 and later · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-23557
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-23557
Patch
https://xenbits.xenproject.org/xsa/advisory-484.html
Mailing List
http://www.openwall.com/lists/oss-security/2026/04/28/11
Patch
http://xenbits.xen.org/xsa/advisory-484.html
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