High severity · published Jun 24, 2026
CVE-2026-52933
io_uring/poll: fix signed comparison in io_poll_get_ownership()
7.8
CVSS
0.1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 4% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
5.15.82 before 5.16; 6.0.11 before 6.1; 6.1.1 before 6.1.175; 6.2 before 6.6.140; 6.7 before 6.12.86; 6.13 before 6.18.27; +4 more · source: NVD
LI
Linux · Linux
a26a35e9019fd70bf3cf647dcfdae87abc7bacea before 81bf96b0abbfa4cd47ea32e12596aed3855fb2f3; a26a35e9019fd70bf3cf647dcfdae87abc7bacea before cf522703d4f194991615763697ae25a3f9539763; a26a35e9019fd70bf3cf647dcfdae87abc7bacea before fc47043f3d9af3efa407665b47f8378ec691ba18; a26a35e9019fd70bf3cf647dcfdae87abc7bacea before ea0697129807d718037f618221037aa0660ee3c5; a26a35e9019fd70bf3cf647dcfdae87abc7bacea before c6d191164dc81838d8dbf452a6000f68c558d1ae; a26a35e9019fd70bf3cf647dcfdae87abc7bacea before 326941b22806cbf2df1fbfe902b7908b368cce42; +5 more · source: vendor
SS
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.6; V3.1.7; V3.1.6; V3.1.7 · source: CISA
SS
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP · Siemens
V3.1.6; V3.1.7; V3.1.6; V3.1.7 · source: CISA
SS
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.6; V3.1.7 · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-52933
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-52933
Patch
https://git.kernel.org/stable/c/326941b22806cbf2df1fbfe902b7908b368cce42
Patch
https://git.kernel.org/stable/c/81bf96b0abbfa4cd47ea32e12596aed3855fb2f3
Patch
https://git.kernel.org/stable/c/c6d191164dc81838d8dbf452a6000f68c558d1ae
Patch
https://git.kernel.org/stable/c/cf522703d4f194991615763697ae25a3f9539763
Patch
https://git.kernel.org/stable/c/ea0697129807d718037f618221037aa0660ee3c5
Patch
https://git.kernel.org/stable/c/fc47043f3d9af3efa407665b47f8378ec691ba18
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