CVE-2026-64031
In the Linux kernel, the following vulnerability has been resolved:
erofs: fix managed cache race for unaligned extents
After unaligned compressed extents were introduced, the following race
could occur:
[Thread 1] [Thread 2]
(z_erofs_fill_bio_vec)
<handle a Z_EROFS_PREALLOCATED_FOLIO folio>
...
filemap_add_folio (1)
(z_erofs_bind_cache)
<the same folio is found..>
..
..
folio_attach_private (2)
filemap_add_folio (3) again
Since (1) is executed but (2) hasn't been executed yet, it's possible
that another thread finds the same managed folio in z_erofs_bind_cache()
for a different pcluster and calls filemap_add_folio() again since
folio->private is still Z_EROFS_PREALLOCATED_FOLIO.
Fix this by explicitly clearing folio->private before making the folio
visible in the managed cache so that another pcluster can simply wait
on the locked managed folio as what we did for other shared cases [1].
This only impacts unaligned data compression (-E48bit with zstd,
for example).
[1] Commit 9e2f9d34dd12 ("erofs: handle overlapped pclusters out of
crafted images properly") was originally introduced to handle crafted
overlapped extents, but it addresses unaligned extents as well.
CSIRTS triage
- What
- Multiple kernel vulnerabilities across architectures and driver subsystems including AMD processor microarchitectural flaws and cache isolation issues.
- Who is affected
- NVIDIA BaseOS systems running affected Linux kernel versions.
- Urgency
- Moderate; privilege escalation and DoS vectors present, primarily requiring local access.
- Action
- Apply USN-8664-1 kernel security update for NVIDIA BaseOS.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.17% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 7% of all EPSS-scored CVEs.
Advisory coverage (6)
- unknownUSN-8664-1: Linux kernel (NVIDIA BaseOS) vulnerabilitiesubuntu · 2026-08-20
- unknownUSN-8663-1: Linux kernel (NVIDIA) vulnerabilitiesubuntu · 2026-08-20
- highUSN-8618-1: Linux kernel vulnerabilitiesubuntu · 2026-07-28
- highUSN-8603-1: Linux kernel (Azure) vulnerabilitiesubuntu · 2026-07-24
- highUSN-8593-1: Linux kernel vulnerabilitiesubuntu · 2026-07-23
- highCVE-2026-64031: In the Linux kernel, the following vulnerability has been resolved: erofs: fix managed cache r…nvd · 2026-07-19
External references
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