xen: XPTI (Xen Page Table Isolation) was introduced to mitigate Meltdown (CVE-2017-5754, one aspect of XSA-254)
CVE-2026-79609 is fixed in xen on 1 platform, first by DEBIAN-CVE-2026-79609, released October 19, 2026. It is not reported as exploited. Patch Radar priority: High.
XPTI (Xen Page Table Isolation) was introduced to mitigate Meltdown (CVE-2017-5754, one aspect of XSA-254). This involves copying 64-bit PV guest page table entries from guest-chosen root page tables to the Xen- chosen one which is in actual use by hardware. To read the guest root page table, the directmap is used. PV guests, however, have a directmap which may not cover all memory; in particular this is the case if any memory extends beyond the 5 TiB (CONFIG_BIGMEM=y: 3.5 TiB) address boundary.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| xen · Debian 12.15 (bookworm) | 4.17.7+13-g2445b30a44-0+deb12u1 | DEBIAN-CVE-2026-79609 | Oct 19, 2026 |
| xen · Debian 13.5 (trixie) | 4.20.4+39-gf1e1321c87-0+deb13u1 | DEBIAN-CVE-2026-79609 | Oct 19, 2026 |
| xen · Debian 14 | 4.20.4+39-gf1e1321c87-1 | DEBIAN-CVE-2026-79609 | Oct 19, 2026 |
| xen · sles 15.7 | 4.20.4_06-150700.3.49.2 | SUSE-SU-2026:4942-1 | Nov 7, 2026 |
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