Cross-guest information exchange via stale TLB entry
Published Sep 8, 2026 · Updated Sep 8, 2026
Information disclosure in Xen 4.13 and later allows guest OS users to exchange data across x86 PV guests through stale TLB entries. Xen scrubs a freed page before flushing the freeing guest's stale TLB entry, leaving that guest able to modify the scrubbed page until reuse triggers a flush. Exploitation requires an x86 PV guest and a host booted with xsm=silo scrub-domheap; the intended isolation between guests is defeated.
Summary
What happened
Information disclosure in Xen 4.13 and later allows guest OS users to exchange data across x86 PV guests through stale TLB entries. Xen scrubs a freed page before flushing the freeing guest's stale TLB entry, leaving that guest able to modify the scrubbed page until reuse triggers a flush. Exploitation requires an x86 PV guest and a host booted with xsm=silo scrub-domheap; the intended isolation between guests is defeated.
The record
- CVE
- CVE-2026-79603
- Published
- Sep 8, 2026
- Updated
- Sep 8, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-664
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 8, 2026CVE publishedPublication date reported by the CVE source.
- Sep 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Attacks
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Technologies
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