CVE-2026-43265 (GCVE-0-2026-43265)

Vulnerability from cvelistv5 – Published: 2026-05-06 11:28 – Updated: 2026-05-11 22:21
VLAI?
Title
KVM: x86: Ignore -EBUSY when checking nested events from vcpu_block()
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ignore -EBUSY when checking nested events from vcpu_block() Ignore -EBUSY when checking nested events after exiting a blocking state while L2 is active, as exiting to userspace will generate a spurious userspace exit, usually with KVM_EXIT_UNKNOWN, and likely lead to the VM's demise. Continuing with the wakeup isn't perfect either, as *something* has gone sideways if a vCPU is awakened in L2 with an injected event (or worse, a nested run pending), but continuing on gives the VM a decent chance of surviving without any major side effects. As explained in the Fixes commits, it _should_ be impossible for a vCPU to be put into a blocking state with an already-injected event (exception, IRQ, or NMI). Unfortunately, userspace can stuff MP_STATE and/or injected events, and thus put the vCPU into what should be an impossible state. Don't bother trying to preserve the WARN, e.g. with an anti-syzkaller Kconfig, as WARNs can (hopefully) be added in paths where _KVM_ would be violating x86 architecture, e.g. by WARNing if KVM attempts to inject an exception or interrupt while the vCPU isn't running.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 26844fee6adee9b1557d2279b0506285de9ee82b , < 78265cd066d73a5cb41c088fcae4a2515e480d97 (git)
Affected: 26844fee6adee9b1557d2279b0506285de9ee82b , < ec3be7dc9391085a2d96700e159d66d1328b7ff6 (git)
Affected: 26844fee6adee9b1557d2279b0506285de9ee82b , < 2657439265d34a911886b916ba8be97ecc117d51 (git)
Affected: 26844fee6adee9b1557d2279b0506285de9ee82b , < 1e88b5f854bdb469424132e0bb44793ad7a7c20a (git)
Affected: 26844fee6adee9b1557d2279b0506285de9ee82b , < 1c957773063ed3264953597e32990a748381caf6 (git)
Affected: 26844fee6adee9b1557d2279b0506285de9ee82b , < ead63640d4e72e6f6d464f4e31f7fecb79af8869 (git)
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Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.77 , ≤ 6.12.* (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.6 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.