CVE-2026-64324
In the Linux kernel, the following vulnerability has been resolved:
udf: validate free block extents against the partition length
udf_free_blocks() checks the logical block number and count against the
partition length, but drops the extent offset from that final bound. A
crafted extent can pass the guard while logicalBlockNum + offset + count
points past the partition, which later indexes past the space bitmap
array.
A single ftruncate(2) on a file backed by such an extent reliably
panics the kernel. This is a local availability issue. On desktop
systems where UDisks/polkit allows the active user to mount removable
UDF media without CAP_SYS_ADMIN, an unprivileged local user can supply
the crafted filesystem and trigger the panic by truncating a writable
file on it. Systems that require root or CAP_SYS_ADMIN to mount the
image have a higher prerequisite.
No confidentiality or integrity impact is claimed: the reproduced
primitive is an out-of-bounds read of a bitmap pointer slot followed by
a kernel panic.
Use the already computed logicalBlockNum + offset + count value for the
partition length check. Also make load_block_bitmap() reject an
out-of-range block group before indexing s_block_bitmap[], so corrupted
callers cannot walk past the flexible array.
CSIRTS triage
- What
- Free block extents are validated against the partition length.
- Who is affected
- Deployments using the UDF filesystem.
- Urgency
- Remediation is recommended to prevent potential filesystem issues, with no current exploitation.
- Action
- Update to the patched version once released.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch CVE-2026-64324
Get an email if CVE-2026-64324 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.
Exploitation outlook
- Low exploitation risk0.16% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
Embed the live status
— this badge updates automatically when the KEV or exploit status changes. How to embed it →
[](https://www.csirts.com/cve/CVE-2026-64324)