CyberSecBulletin
CVE-2026-53358NVD status: Modified

Linux: Improper Locking

Published Updated By the CyberSecBulletin desk

CVE-2026-53358 is a high-severity improper locking vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 3634cbdc2eb414b69ffa752ddbe5e0458518e321, e1c100e2d61bd8c718b7d91fe3e050780a9bf72d, deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9 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 0.28% 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 3634cbdc2eb414b69ffa752ddbe5e0458518e321 or e1c100e2d61bd8c718b7d91fe3e050780a9bf72d or deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9 or 89dec92041717b027216e110599e4f6d6c921b79, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 3634cbdc2eb414b69ffa752ddbe5e0458518e321; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, e1c100e2d61bd8c718b7d91fe3e050780a9bf72d; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 89dec92041717b027216e110599e4f6d6c921b79; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 50dfec218808b148ab4247b1858031b7a32015c5; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 859d3ace791ed878ae9ba5522c7844d960da8f88; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 7555fd885a0603f50e49a655850a1f2bd8a25398; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 8c8e620467a7b51562dbcefbd1f09f288d7d710d; and 1 more ranges3634cbdc2eb414b69ffa752ddbe5e0458518e321, e1c100e2d61bd8c718b7d91fe3e050780a9bf72d, deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9, 89dec92041717b027216e110599e4f6d6c921b79, 50dfec218808b148ab4247b1858031b7a32015c5, 859d3ace791ed878ae9ba5522c7844d960da8f88
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel3.4 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.93; 6.13 up to, but not including, 6.18.35; 6.19 up to, but not including, 7.0.12; 7.15.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35

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
AdjacentThe attacker must be on the same local network segment.
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
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:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: use chan timer to close channels in cleanup_listen() l2cap_chan_close() removes the channel from conn->chan_l, which must be done under conn->lock. cleanup_listen() runs under the parent sk_lock, so acquiring conn->lock would invert the established conn->lock -> chan->lock -> sk_lock order. Instead of calling l2cap_chan_close() directly, schedule l2cap_chan_timeout with delay 0 to close the channel asynchronously. The timeout handler already acquires conn->lock and chan->lock in the correct order. The timer is only armed when chan->conn is still set: if it is already NULL, l2cap_conn_del() has already processed this channel (l2cap_chan_del + l2cap_sock_teardown_cb + l2cap_sock_close_cb), so there is nothing left to do. If l2cap_conn_del() races in after the timer is armed, __clear_chan_timer() inside l2cap_chan_del() cancels it; if the timer has already fired, the handler returns harmlessly because chan->conn was cleared.

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.

More Improper Locking vulnerabilities (CWE-667)

Timeline

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

References

Recent Improper Locking vulnerabilities

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