CyberSecBulletin
CVE-2026-52933NVD status: Modified

Linux: Loop with Unreachable Exit Condition

Published Updated By the CyberSecBulletin desk

CVE-2026-52933 is a high-severity loop with unreachable exit condition 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 81bf96b0abbfa4cd47ea32e12596aed3855fb2f3, cf522703d4f194991615763697ae25a3f9539763, fc47043f3d9af3efa407665b47f8378ec691ba18 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 0.15% 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 81bf96b0abbfa4cd47ea32e12596aed3855fb2f3 or cf522703d4f194991615763697ae25a3f9539763 or fc47043f3d9af3efa407665b47f8378ec691ba18 or ea0697129807d718037f618221037aa0660ee3c5, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.16 or 6.1 or 6.1.175 or 6.6.140, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxa26a35e9019fd70bf3cf647dcfdae87abc7bacea up to, but not including, 81bf96b0abbfa4cd47ea32e12596aed3855fb2f3; a26a35e9019fd70bf3cf647dcfdae87abc7bacea up to, but not including, cf522703d4f194991615763697ae25a3f9539763; a26a35e9019fd70bf3cf647dcfdae87abc7bacea up to, but not including, fc47043f3d9af3efa407665b47f8378ec691ba18; a26a35e9019fd70bf3cf647dcfdae87abc7bacea up to, but not including, ea0697129807d718037f618221037aa0660ee3c5; a26a35e9019fd70bf3cf647dcfdae87abc7bacea up to, but not including, c6d191164dc81838d8dbf452a6000f68c558d1ae; a26a35e9019fd70bf3cf647dcfdae87abc7bacea up to, but not including, 326941b22806cbf2df1fbfe902b7908b368cce42; 4b702b7d11ce1b9d26fc6d7c5a7ef4ac1d455048; bc4e6ee16778149811333a969a7a893d4cc110c5; and 3 more ranges81bf96b0abbfa4cd47ea32e12596aed3855fb2f3, cf522703d4f194991615763697ae25a3f9539763, fc47043f3d9af3efa407665b47f8378ec691ba18, ea0697129807d718037f618221037aa0660ee3c5, c6d191164dc81838d8dbf452a6000f68c558d1ae, 326941b22806cbf2df1fbfe902b7908b368cce42
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)V3.1.6 and later; V3.1.7 and laterNot stated
LinuxLinux Kernel5.15.82 up to, but not including, 5.16; 6.0.11 up to, but not including, 6.1; 6.1.1 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.140; 6.7 up to, but not including, 6.12.86; 6.13 up to, but not including, 6.18.27; 6.19 up to, but not including, 7.0.4; 6.15.16, 6.1, 6.1.175, 6.6.140, 6.12.86, 6.18.27

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: io_uring/poll: fix signed comparison in io_poll_get_ownership() io_poll_get_ownership() uses a signed comparison to check whether poll_refs has reached the threshold for the slowpath: if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomic_read() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath.

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

The underlying weakness: Loop with Unreachable Exit Condition

The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

More Loop with Unreachable Exit Condition vulnerabilities (CWE-835)

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 Loop with Unreachable Exit Condition vulnerabilities

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