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Fencer Vulns
high 7.8

CVE-2026-64057 json

afs: Fix the locking used by afs_get_link()

published 2026-07-19 3 mo ago modified 2026-10-15 25 d ago also EUVD-2026-45630

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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

afs: Fix the locking used by afs_get_link()

The afs filesystem in the kernel doesn't do locking correctly for symbolic links. There are a number of problems:

(1) It doesn't do any locking around afs_read_single() to prevent races between multiple ->get_link() calls, thereby allowing the possibility of leaks.

(2) It doesn't use RCU barriering when accessing the buffer pointers during RCU pathwalk.

(3) It can race with another thread updating the contents of the symlink if a third party updated it on the server.

Fix this by the following means:

(0) Move symlink handling into its own file as this makes it more complicated.

(1) Take the validate_lock around afs_read_single() to prevent races between multiple ->get_link() calls.

(2) Keep a separate copy of the symlink contents with an rcu_head. This is always going to be a lot smaller than a page, so it can be kmalloc'd and save quite a bit of memory. It also needs a refcount for non-RCU pathwalk.

(3) Split the symlink read and write-to-cache routines in afs from those for directories.

(4) Discard the I/O buffer as soon as the write-to-cache completes as this is a full page (plus a folio_queue).

(5) If there's no cache, discard the I/O buffer immediately after reading and copying if there is no cache.

Patch / fix

  • Linux Linux 6.18.57, 7.0.11, 7.1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-64057

  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1008.8
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1003.4
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1015.15
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-28.28.1

ubuntu advisories UBUNTU-CVE-2026-64057

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-2026-64057 updated cvss 7.0

kernel: afs: Fix the locking used by afs_get_link()

  • Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available
  • 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 Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 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

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.