Linux Kernel KVM ARM64 vgic-its Refcount Mismanagement on Concurrent Invalidation
CVE-2026-46316 Published on June 9, 2026
KVM: arm64: vgic-its: Drop the translation cache reference only for the erased entry
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: vgic-its: Drop the translation cache reference only for the erased entry
vgic_its_invalidate_cache() walks the per-ITS translation cache with
xa_for_each() and drops the cache's reference on each entry with
vgic_put_irq(). It puts the iterated pointer, though, rather than the
value returned by xa_erase().
The function is called from contexts that do not exclude one another: the
ITS command handlers hold its_lock, the GITS_CTLR write path holds
cmd_lock, and the path that clears EnableLPIs in a redistributor's
GICR_CTLR holds neither. Two or more of them can drain the same cache
concurrently, and if each one observes the same entry, erases it and then
puts it, the single reference the cache holds on that entry is dropped
more than once. The entry can then be freed while an ITE still maps it.
xa_erase() is atomic and returns the previous entry, so put only the entry
that this context actually removed. The cache reference is then dropped
exactly once per entry even when the invalidations run concurrently, and
the behavior is unchanged when only one context runs.
Vulnerability Analysis
CVE-2026-46316 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Improper Update of Reference Count
The software uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. Reference counts can be used when tracking how many objects contain a reference to a particular resource, such as in memory management or garbage collection. When the reference count reaches zero, the resource can be de-allocated or reused because there are no more objects that use it. If the reference count accidentally reaches zero, then the resource might be released too soon, even though it is still in use. If all objects no longer use the resource, but the reference count is not zero, then the resource might not ever be released.
Products Associated with CVE-2026-46316
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Affected Versions
Linux:- Version 8201d1028caa4fae88e222c4e8cf541fdf45b821 and below b7b72e88046328c9fdc638fe887d4240257dd5dc is affected.
- Version 8201d1028caa4fae88e222c4e8cf541fdf45b821 and below 2bbc395e81bd29c543a0529a678327e932a7ec69 is affected.
- Version 8201d1028caa4fae88e222c4e8cf541fdf45b821 and below 9121f4605ab94969f62d1b5714ca3c6c69bd202f is affected.
- Version 8201d1028caa4fae88e222c4e8cf541fdf45b821 and below 13031fb6b8357fbbcded2a7f4cba73e4781ee594 is affected.
- Version 6.10 is affected.
- Before 6.10 is unaffected.
- Version 6.12.93, <= 6.12.* is unaffected.
- Version 6.18.35, <= 6.18.* is unaffected.
- Version 7.0.12, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.