🛡️ CVE-2026-42493 on Debian — xen

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

Addressing certain issues, in particular related to operations which may take excessively long and therefore would need preemption, has turned out overly costly. Since alternatives (HVM/PVH: HAP, PV: shim) are commonly available, the decision was to deprecate the functionality, while still retaining it for people to use at their own (security) risk. Memory-wise small enough guests may still be okay to run.

Distribution advisory

This page covers CVE-2026-42493 as tracked by Debian, for the package xen. The fix is available in version 4.20.3+127-gc42374a105-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

DEBIAN-CVE-2026-42493 is classified as CWE-400: Uncontrolled Resource Consumption. A request can consume memory, CPU or storage without limit, exhausting capacity for everyone else.

Affected software

DEBIAN-CVE-2026-42493 is recorded against 1 package.

xen (fixed in 4.20.3+127-gc42374a105-1)

Timeline and source

Published on 28 July 2026 and last revised on 9 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

Details

Severity Unknown

CVSS Score N/A

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

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2026-07-28

Updated 2026-08-20

Modified 2026-08-09

Fix URL N/A

Affected Packages

Software	From version	Fixed in
xen	—	4.20.3+127-gc42374a105-1

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2026-42493

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