Quick answers
- Is CVE-2026-42493 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-42493 being exploited in the wild.
- How severe is CVE-2026-42493?
- Informational severity, published 28 July 2026.
- Which products and versions are affected?
- Xen Project Xen All x86 versions with SHADOW_PAGING=y; versions prior to 4.7; 4.17.x; 4.18.x; 4.20.x; 4.21.x; 4.22.0.
- Is there a fix for CVE-2026-42493?
- A patch was published on 2026-07-28. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-42493 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-42493?
- Check whether you run Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A denial-of-service vulnerability exists in Xen's x86 shadow paging implementation. Certain operations within the shadow paging code can take an excessively long time to complete and lack proper preemption points, allowing a guest VM to monopolize CPU resources or trigger host hangs. The Xen Project has determined that a full fix is too costly and has instead deprecated the functionality (XSA-495). The vulnerability affects all x86 systems where SHADOW_PAGING is enabled. Mitigation involves using Hardware Assisted Paging (HAP) for HVM/PVH guests, though no direct mitigation exists for PV guests other than disabling shadow paging support entirely in the hypervisor build.
Affected products
- Xen Project Xen All x86 versions with SHADOW_PAGING=y; versions prior to 4.7; 4.17.x; 4.18.x; 4.20.x; 4.21.x; 4.22.0
Timeline
- 2026-07-28: disclosed
- 2026-07-28: advisory: XSA-495 published
- 2026-07-28: patched