Inverted bitmap validation in invalidate_l2_cached_ept

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

4.6 · CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-20765: 0.30% estimated exploitation activity in the next 30 days; percentile 23.41 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

`tdx_guest::tdcall::invalidate_l2_cached_ept()` takes a bitmap that selects the L2 VMs whose cached EPT translations should be invalidated. Bits 1 through 3 select L2 VMs 1 through 3, and all other bits are reserved. The input check was inverted: if l2_vm_idx_bitmap & !0b1110 == 0 { return Err(TdCallError::TdxOperandInvalid); } `l2_vm_idx_bitmap & !0b1110` isolates the bits that are not allowed. A result of zero means the bitmap is valid, and the function returned an error in that case. Every valid bitmap, such as `0b0010` or `0b1110`, was therefore rejected with `TdxOperandInvalid`. Bitmaps with reserved bits set, such as `0b0001` or `0b1_0000`, were forwarded to the TDX module. Intel describes the issue as an incorrect comparison and classifies it as escalation of privilege, with a CVSS 4.0 base score of 4.6, in INTEL-SA-01462. The flaw was corrected in commit `311d33b`,…

Published by the source

11 Aug 2026, 12:00 UTC

Last modified by the source

11 Nov 2026, 08:45 UTC

Source last checked

12 Nov 2026, 06:15 UTC

1. Revision 1 · created · 12 Nov 2026

   Published from osv record RUSTSEC-2026-0484

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# Patch Next advisory brief: CVE-2026-20765

Advisory: Inverted bitmap validation in `invalidate_l2_cached_ept`
IDs: CVE-2026-20765, GHSA-56j3-r4r2-x3x6
Record: https://patchnext.com/advisories/cve-2026-20765 (revision 1, source checked 12 Nov 2026, 06:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tdx-guest 0.3.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io tdx-guest: affected >= 0.1.8, < 0.3.1; fixed in 0.3.1

## Suggested inspection (read-only)
- crates.io tdx-guest: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tdx-guest.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/RUSTSEC-2026-0484 (OSV record RUSTSEC-2026-0484 lists affected ranges: crates.io tdx-guest >=0.1.8 <0.3.1 (fixed))

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