7.8
/ 10
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Description
In the Linux kernel, the following vulnerability has been resolved:
xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()
The TX metadata area resides in the UMEM buffer which is memory-mapped
and concurrently writable by userspace. In xsk_skb_metadata(),
csum_start and csum_offset are read from shared memory for bounds
validation, then read again for skb assignment. A malicious userspace
application can race to overwrite these values between the two reads,
bypassing the bounds check and causing out-of-bounds memory access
during checksum computation in the transmit path.
Fix this by reading csum_start and csum_offset into local variables
once, then using the local copies for both validation and assignment.
Note that other metadata fields (flags, launch_time) and the cached
csum fields may be mutually inconsistent due to concurrent userspace
writes, but this is benign: the only security-critical invariant is
that each field's validated value is the same one used, which local
caching guarantees.
xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()
The TX metadata area resides in the UMEM buffer which is memory-mapped
and concurrently writable by userspace. In xsk_skb_metadata(),
csum_start and csum_offset are read from shared memory for bounds
validation, then read again for skb assignment. A malicious userspace
application can race to overwrite these values between the two reads,
bypassing the bounds check and causing out-of-bounds memory access
during checksum computation in the transmit path.
Fix this by reading csum_start and csum_offset into local variables
once, then using the local copies for both validation and assignment.
Note that other metadata fields (flags, launch_time) and the cached
csum fields may be mutually inconsistent due to concurrent userspace
writes, but this is benign: the only security-critical invariant is
that each field's validated value is the same one used, which local
caching guarantees.
Basic Information
ID
CVE-2026-53250
Source
Linux
Published
Jun 25, 2026 at 08:39
Modified
Jun 28, 2026 at 06:40
Affected Product
Vendor
Linux
Product
Linux
Version
48eb03dd26304c24f03bdbb9382e89c8564e71df
Affected Versions
Linux Linux 48eb03dd26304c24f03bdbb9382e89c8564e71df
Linux Linux 48eb03dd26304c24f03bdbb9382e89c8564e71df
Linux Linux 48eb03dd26304c24f03bdbb9382e89c8564e71df
Linux Linux 6.8
Linux Linux 48eb03dd26304c24f03bdbb9382e89c8564e71df
Linux Linux 48eb03dd26304c24f03bdbb9382e89c8564e71df
Linux Linux 6.8