Skip to main content
VulnerabilityPublished Updated

CVE-2026-74506: Linux kernel · afs: Fix UAF when sending a message

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in daaa726b14fc3026a6b328614d312b698f62f391 : patch Linux kernel soon.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in daaa726b14fc3026a6b328614d312b698f62f391, cbb0d3da042c01082f40166fdc99bf1752db72be, c0d3b81f703b2a9e37fe1347610a50cdf0078c27 +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to daaa726b14fc3026a6b328614d312b698f62f391, cbb0d3da042c01082f40166fdc99bf1752db72be, c0d3b81f703b2a9e37fe1347610a50cdf0078c27 or 4af1ec68d54b3871155914d584fb10669c41a861.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ e49c7b2f6de7ff81ca34c56e4eeb4fa740c099f2, < daaa726b14fc3026a6b328614d312b698f62f391
Fixed in
  • daaa726b14fc3026a6b328614d312b698f62f391
LinuxLinuxAffected
  • ≥ e49c7b2f6de7ff81ca34c56e4eeb4fa740c099f2, < cbb0d3da042c01082f40166fdc99bf1752db72be
Fixed in
  • cbb0d3da042c01082f40166fdc99bf1752db72be
LinuxLinuxAffected
  • ≥ e49c7b2f6de7ff81ca34c56e4eeb4fa740c099f2, < c0d3b81f703b2a9e37fe1347610a50cdf0078c27
Fixed in
  • c0d3b81f703b2a9e37fe1347610a50cdf0078c27
LinuxLinuxAffected
  • ≥ e49c7b2f6de7ff81ca34c56e4eeb4fa740c099f2, < 4af1ec68d54b3871155914d584fb10669c41a861
Fixed in
  • 4af1ec68d54b3871155914d584fb10669c41a861
LinuxLinuxAffected
  • =5.8
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: afs: Fix UAF when sending a message In afs_make_call(), there's a race with async call reception and destruction. If a call is dispatched that doesn't have call->write_iter set (used to specify the data content for FS.StoreData), then the first rxrpc_kernel_send_data() will not set MSG_MORE in the msghdr. Once rxrpc_send_data() queues the last request packet, the response could come in at any time and cause the call to be completed and put. However, afs_make_call() will look at the call again to see it ->write_iter should be handled - something it's only allowed to do if it has its own ref on the call. Whilst this is the case for synchronous calls, it isn't true for async calls such as FS.FetchData. There's also a potential UAF in afs_make_call() in the event that an asynchronous call is being sent, but the call fails in some way (e.g. it gets aborted from the server). The problem there is that afs_make_call() tries to abort a call if the rxrpc send fails, but the asynchronous notification from rxrpc may have caused the afs_call to be torn down. generic/650 plays games with randomly taking CPUs offline, and can interject a significant delay such that the call is deallocated before afs_make_call() gets to check call->write_iter - and a UAF ensues (caught by KASAN). BUG: KASAN: slab-use-after-free in afs_make_call+0x1c90/0x2210 [kafs] Read of size 8 at addr ffff888035e050e8 by task fsstress/1409 Fix this by making afs_make_op_call() give the op->call its own ref rather than transferring the caller's ref to it and then dropping the ref when afs_make_call() returns. This also means that the afs_make_call() func never loses its ref on the call now.

References

Community reviews

Loading reviews…