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Fencer Vulns
no cvss —

CVE-2025-68299 json

afs: Fix delayed allocation of a cell's anonymous key

published 2025-12-16 10 mo ago modified 2026-10-14 25 d ago also EUVD-2025-203781

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

afs: Fix delayed allocation of a cell's anonymous key

The allocation of a cell's anonymous key is done in a background thread along with other cell setup such as doing a DNS upcall. In the reported bug, this is triggered by afs_parse_source() parsing the device name given to mount() and calling afs_lookup_cell() with the name of the cell.

The normal key lookup then tries to use the key description on the anonymous authentication key as the reference for request_key() - but it may not yet be set and so an oops can happen.

This has been made more likely to happen by the fix for dynamic lookup failure.

Fix this by firstly allocating a reference name and attaching it to the afs_cell record when the record is created. It can share the memory allocation with the cell name (unfortunately it can't just overlap the cell name by prepending it with "afs@" as the cell name already has a '.' prepended for other purposes). This reference name is then passed to request_key().

Secondly, the anon key is now allocated on demand at the point a key is requested in afs_request_key() if it is not already allocated. A mutex is used to prevent multiple allocation for a cell.

Thirdly, make afs_request_key_rcu() return NULL if the anonymous key isn't yet allocated (if we need it) and then the caller can return -ECHILD to drop out of RCU-mode and afs_request_key() can be called.

Note that the anonymous key is kind of necessary to make the key lookup cache work as that doesn't currently cache a negative lookup, but it's probably worth some investigation to see if NULL can be used instead.

Patch / fix

  • Linux Linux 6.17.11
  • linux Debian 14 6.17.11-1

debian advisories DEBIAN-CVE-2025-68299

  • linux Ubuntu 25.10 6.17.0-19.19
  • linux-aws Ubuntu 25.10 6.17.0-1009.9
  • linux-gcp Ubuntu 25.10 6.17.0-1009.9
  • linux-azure Ubuntu 25.10 6.17.0-1010.10
  • linux-raspi Ubuntu 25.10 6.17.0-1010.10
  • linux-riscv Ubuntu 25.10 6.17.0-19.19.1
  • linux-oracle Ubuntu 25.10 6.17.0-1009.9
  • linux-aws-6.17 Ubuntu 24.04 LTS 6.17.0-1009.9~24.04.2

ubuntu advisories UBUNTU-CVE-2025-68299

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-68299 updated cvss 5.5

kernel: Linux kernel: Denial of Service in AFS due to delayed key allocation

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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