Xen Grant Table GNTTABOP_cache_flush integer overflow

Summaryinfo

A vulnerability categorized as critical has been discovered in Xen. This affects the function GNTTABOP_cache_flush of the component Grant Table. Such manipulation leads to integer overflow. This vulnerability is uniquely identified as CVE-2026-102699. The attack can be launched remotely. No exploit exists. It is best practice to apply a patch to resolve this issue.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Xen (affected version unknown). Affected by this issue is the function GNTTABOP_cache_flush of the component Grant Table. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is integrity, and availability. CVE summarizes:

[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] 1) XSA-437 (CVE-2023-34321) addressed issues with overflows in calculations involved in guests flushing caches through GNTTABOP_cache_flush. Unfortunately the fix there introduced a calculation which may underflow, resulting in a loop which would - at least on 64-bit Arm - take excessively long, and which would likely eventually crash the hypervisor. This is CVE-2026-102699. 2) GNTTABOP_cache_flush may be issued on memory mapped from another domain using the grant table interface. However there was no restriction to disallow the use of invalidate-without-clean against read-only grant mappings, which may corrupt the granted memory. This is CVE-2026-102702.

The advisory is available at xenbits.xenproject.org. This vulnerability is handled as CVE-2026-102699 since 09/29/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 10/13/2026).

Applying the patch XSA-437 is able to eliminate this problem.

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Productinfo

Type

• Virtualization Software

Name

• Xen

License

• open-source

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