Linux: Improper Locking
CVE-2026-31598 is a high-severity improper locking vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 297d8d7bb6a2bf133d3a3636edbdf94101cbd719, 32630dee18c6bb2175c8a865a474749492eaf19c, 93f35419eb84d58820040642cb6e7528fe4aba7a 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 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 297d8d7bb6a2bf133d3a3636edbdf94101cbd719 or 32630dee18c6bb2175c8a865a474749492eaf19c or 93f35419eb84d58820040642cb6e7528fe4aba7a or 4b80b5a838a32437f2cae0662578bac216a2c51a, whichever matches your release line, or a later version.
- 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.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, 297d8d7bb6a2bf133d3a3636edbdf94101cbd719; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, 32630dee18c6bb2175c8a865a474749492eaf19c; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, 93f35419eb84d58820040642cb6e7528fe4aba7a; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, 4b80b5a838a32437f2cae0662578bac216a2c51a; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, 2b884d52273c60c298bd570163e8053657bbaff6; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, bc0fb5c7d54c78be43a536df0e20dee32adb27d3; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, f9fb1a7b635849322e1d7b7b6b26389778ec8e82; a86a72a4a4e0ec109a98e2737948864ed6794bf7 up to, but not including, e049f7a9bd80b7319590789ea5e1c523d6339d91; and 2 more ranges | 297d8d7bb6a2bf133d3a3636edbdf94101cbd719, 32630dee18c6bb2175c8a865a474749492eaf19c, 93f35419eb84d58820040642cb6e7528fe4aba7a, 4b80b5a838a32437f2cae0662578bac216a2c51a, 2b884d52273c60c298bd570163e8053657bbaff6, bc0fb5c7d54c78be43a536df0e20dee32adb27d3 |
| Linux | Linux Kernel | 4.6 up to, but not including, 6.6.136; 6.7 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, 7.0.1 | 6.6.136, 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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix possible deadlock between unlink and dio_end_io_write ocfs2_unlink takes orphan dir inode_lock first and then ip_alloc_sem, while in ocfs2_dio_end_io_write, it acquires these locks in reverse order. This creates an ABBA lock ordering violation on lock classes ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] and ocfs2_file_ip_alloc_sem_key. Lock Chain #0 (orphan dir inode_lock -> ip_alloc_sem): ocfs2_unlink ocfs2_prepare_orphan_dir ocfs2_lookup_lock_orphan_dir inode_lock(orphan_dir_inode) <- lock A __ocfs2_prepare_orphan_dir ocfs2_prepare_dir_for_insert ocfs2_extend_dir ocfs2_expand_inline_dir down_write(&oi->ip_alloc_sem) <- Lock B Lock Chain #1 (ip_alloc_sem -> orphan dir inode_lock): ocfs2_dio_end_io_write down_write(&oi->ip_alloc_sem) <- Lock B ocfs2_del_inode_from_orphan() inode_lock(orphan_dir_inode) <- Lock A Deadlock Scenario: CPU0 (unlink) CPU1 (dio_end_io_write) ------ ------ inode_lock(orphan_dir_inode) down_write(ip_alloc_sem) down_write(ip_alloc_sem) inode_lock(orphan_dir_inode) Since ip_alloc_sem is to protect allocation changes, which is unrelated with operations in ocfs2_del_inode_from_orphan. So move ocfs2_del_inode_from_orphan out of ip_alloc_sem to fix the deadlock.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Locking
The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.
How developers prevent this class of flaw
- Use industry standard APIs to implement locking mechanism.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2b884d52273c60c298bd570163e8053657bbaff6
- git.kernel.org/stable/c/4b80b5a838a32437f2cae0662578bac216a2c51a
- git.kernel.org/stable/c/b02da26a992db0c0e2559acbda0fc48d4a2fd337
- git.kernel.org/stable/c/bc0fb5c7d54c78be43a536df0e20dee32adb27d3
- git.kernel.org/stable/c/e049f7a9bd80b7319590789ea5e1c523d6339d91
- git.kernel.org/stable/c/f9fb1a7b635849322e1d7b7b6b26389778ec8e82
Other references
Recent Improper Locking vulnerabilities
- 7.8 High severity
- 8.8 High severity
- 7.5 High severity
- 7.1 High severity
- 7.5 High severity
- 7.5 High severity
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