CyberSecBulletin
CVE-2026-31580NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-31580 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 81f44ed8c3f54abb7561ece774ea4cca5070b2f2, f50e7c325ab1207fe941555bcff659f6d7050572, 9467d360be70e6ee55b0c1cd2a1f1424f57b5b85 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 81f44ed8c3f54abb7561ece774ea4cca5070b2f2 or f50e7c325ab1207fe941555bcff659f6d7050572 or 9467d360be70e6ee55b0c1cd2a1f1424f57b5b85 or 47fa09fe7f3e09df28a51cb2cbd8f5d2f7f6edc1, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.136 or 6.12.83 or 6.18.24 or 6.19.14, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxcafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, 81f44ed8c3f54abb7561ece774ea4cca5070b2f2; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, f50e7c325ab1207fe941555bcff659f6d7050572; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, 9467d360be70e6ee55b0c1cd2a1f1424f57b5b85; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, 47fa09fe7f3e09df28a51cb2cbd8f5d2f7f6edc1; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, add4982510f3b7c318a2dd7438bdc9c63171e753; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, 2d6965581e164fa2ba3f7652ddae5535f6336576; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, 4f71c8ba2dc009042493021d94a9718fbe2ebf27; cafe563591446cf80bfbc2fe3bc72a2e36cf1060 up to, but not including, 383f7fec0de8cee1cf7ae1f9d9f14044a61f10f9; and 2 more ranges81f44ed8c3f54abb7561ece774ea4cca5070b2f2, f50e7c325ab1207fe941555bcff659f6d7050572, 9467d360be70e6ee55b0c1cd2a1f1424f57b5b85, 47fa09fe7f3e09df28a51cb2cbd8f5d2f7f6edc1, add4982510f3b7c318a2dd7438bdc9c63171e753, 2d6965581e164fa2ba3f7652ddae5535f6336576
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernelbefore 6.6.136; 6.12 up to, but not including, 6.12.83; 6.13 up to, but not including, 6.18.24; 6.19 up to, but not including, 6.19.14; 7.0 up to, but not including, 7.0.16.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

In the Linux kernel, the following vulnerability has been resolved: bcache: fix cached_dev.sb_bio use-after-free and crash In our production environment, we have received multiple crash reports regarding libceph, which have caught our attention: ``` [6888366.280350] Call Trace: [6888366.280452] blk_update_request+0x14e/0x370 [6888366.280561] blk_mq_end_request+0x1a/0x130 [6888366.280671] rbd_img_handle_request+0x1a0/0x1b0 [rbd] [6888366.280792] rbd_obj_handle_request+0x32/0x40 [rbd] [6888366.280903] __complete_request+0x22/0x70 [libceph] [6888366.281032] osd_dispatch+0x15e/0xb40 [libceph] [6888366.281164] ? inet_recvmsg+0x5b/0xd0 [6888366.281272] ? ceph_tcp_recvmsg+0x6f/0xa0 [libceph] [6888366.281405] ceph_con_process_message+0x79/0x140 [libceph] [6888366.281534] ceph_con_v1_try_read+0x5d7/0xf30 [libceph] [6888366.281661] ceph_con_workfn+0x329/0x680 [libceph] ``` After analyzing the coredump file, we found that the address of dc->sb_bio has been freed. We know that cached_dev is only freed when it is stopped. Since sb_bio is a part of struct cached_dev, rather than an alloc every time. If the device is stopped while writing to the superblock, the released address will be accessed at endio. This patch hopes to wait for sb_write to complete in cached_dev_free. It should be noted that we analyzed the cause of the problem, then tell all details to the QWEN and adopted the modifications it made.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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