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Fencer Vulns
high 7.8

CVE-2026-52933 json

io_uring/poll: fix signed comparison in io_poll_get_ownership()

published 2026-06-24 4 mo ago modified 2026-10-19 20 d ago also EUVD-2026-38703

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 5.16, 6.1, 6.1.175, 6.6.140, 6.12.86, 6.18.27, 7.0.4, 7.1
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.86-1
  • linux Debian 14 7.0.4-1

debian advisories DEBIAN-CVE-2026-52933

  • linux Ubuntu 22.04 LTS 5.15.0-198.208
  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux Ubuntu 26.04 LTS 7.0.0-27.27
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1008.8
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72

ubuntu advisories UBUNTU-CVE-2026-52933

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kpatch-patch-6_12_0-211_16_1 RHEL 10.2 2-10.el10_2
  • kpatch-patch-6_12_0-211_49_1 RHEL 10.2 2-2.el10_2
  • kpatch-patch-5_14_0-687_10_1 RHEL 9 1-10.el9_8
  • kpatch-patch-5_14_0-687_42_1 RHEL 9 1-1.el9_8
  • kernel RHEL 9 5.14.0-687.45.1.el9_8
  • rv RHEL 9 5.14.0-687.45.1.el9_8
  • perf RHEL 9 5.14.0-687.45.1.el9_8
  • rtla RHEL 9 5.14.0-687.45.1.el9_8

red hat advisories RHSA-2026:82326RHSA-2026:81451RHSA-2026:81452RHSA-2026:81449RHSA-2026:68100RHSA-2026:67114

  • kernel-64kb SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS, SLE High Performance Computing 15 SP5-ESPOS 5.14.21-150500.55.182.1
  • kernel-syms SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 5.14.21-150500.55.182.1
  • kernel-source SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 5.14.21-150500.55.182.1
  • kernel-default SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +3 more 5.14.21-150500.55.182.1
  • kernel-obs-build SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 5.14.21-150500.55.182.1
  • kernel-default-base SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 5.14.21-150500.55.182.1.150500.6.85.2
  • kernel-rt SLE Micro 5.5 5.14.21-150500.13.156.1
  • kernel-source-rt SLE Micro 5.5 5.14.21-150500.13.156.1

suse advisories SUSE-SU-2026:3595-1SUSE-SU-2026:3617-1SUSE-SU-2026:22810-1SUSE-SU-2026:22809-1SUSE-SU-2026:22904-1SUSE-SU-2026:22903-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.36.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.36.1

opensuse advisories openSUSE-SU-2026:21388-1

  • kernel AlmaLinux 9 5.14.0-687.45.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.45.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.45.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.45.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.45.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.45.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.45.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.45.1.el9_8

almalinux advisories ALSA-2026:64808

  • kernel Rocky Linux 10 6.12.0-211.52.1.el10_2
  • kernel Rocky Linux 9 5.14.0-687.45.1.el9_8

rocky linux advisories RLSA-2026:64775RLSA-2026:64808

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-52933 updated cvss 7.8

kernel: io_uring/poll: fix signed comparison in io_poll_get_ownership()

  • Red Hat CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.140.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.140.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.140.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.140.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.140.1.el9_6
    fixed: vendor fix RHSA-2026:65708
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.45.1.el9_8, perf 5.14.0-687.45.1.el9_8, rtla 5.14.0-687.45.1.el9_8, python3-perf 5.14.0-687.45.1.el9_8, kernel-devel-matched 5.14.0-687.45.1.el9_8, kernel-64k-devel-matched 5.14.0-687.45.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:64808
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.52.1.el10_2, perf 6.12.0-211.52.1.el10_2, rtla 6.12.0-211.52.1.el10_2, python3-perf 6.12.0-211.52.1.el10_2, kernel-devel-matched 6.12.0-211.52.1.el10_2, kernel-64k-devel-matched 6.12.0-211.52.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:64775
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.150.1.el9_4, perf 5.14.0-427.150.1.el9_4, rtla 5.14.0-427.150.1.el9_4, kernel-devel-matched 5.14.0-427.150.1.el9_4, kernel-64k-devel-matched 5.14.0-427.150.1.el9_4, kernel-debug-devel-matched 5.14.0-427.150.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:68100
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.104.1.el10_0, perf 6.12.0-55.104.1.el10_0, rtla 6.12.0-55.104.1.el10_0, python3-perf 6.12.0-55.104.1.el10_0, kernel-devel-matched 6.12.0-55.104.1.el10_0, kernel-64k-devel-matched 6.12.0-55.104.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:67114
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.140.1.el9_6, perf 5.14.0-570.140.1.el9_6, rtla 5.14.0-570.140.1.el9_6, python3-perf 5.14.0-570.140.1.el9_6, kernel-devel-matched 5.14.0-570.140.1.el9_6, kernel-64k-devel-matched 5.14.0-570.140.1.el9_6, +7 more
    fixed: vendor fix RHSA-2026:65708
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.45.1.el9_8, kernel-64k 5.14.0-687.45.1.el9_8, kernel-core 5.14.0-687.45.1.el9_8, kernel-tools 5.14.0-687.45.1.el9_8, kernel-modules 5.14.0-687.45.1.el9_8, kernel-64k-core 5.14.0-687.45.1.el9_8, +29 more
    fixed: vendor fix RHSA-2026:64808
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.52.1.el10_2, kernel-64k 6.12.0-211.52.1.el10_2, kernel-core 6.12.0-211.52.1.el10_2, kernel-tools 6.12.0-211.52.1.el10_2, kernel-modules 6.12.0-211.52.1.el10_2, kernel-64k-core 6.12.0-211.52.1.el10_2, +30 more
    fixed: vendor fix RHSA-2026:64775
show 17 more
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.150.1.el9_4, kernel 5.14.0-427.150.1.el9_4, kernel-64k 5.14.0-427.150.1.el9_4, kernel-core 5.14.0-427.150.1.el9_4, kernel-tools 5.14.0-427.150.1.el9_4, python3-perf 5.14.0-427.150.1.el9_4, +33 more
    fixed: vendor fix RHSA-2026:68100
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.104.1.el10_0, kernel-64k 6.12.0-55.104.1.el10_0, kernel-core 6.12.0-55.104.1.el10_0, kernel-tools 6.12.0-55.104.1.el10_0, kernel-modules 6.12.0-55.104.1.el10_0, kernel-64k-core 6.12.0-55.104.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:67114
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.140.1.el9_6, kernel-64k 5.14.0-570.140.1.el9_6, kernel-core 5.14.0-570.140.1.el9_6, kernel-tools 5.14.0-570.140.1.el9_6, kernel-modules 5.14.0-570.140.1.el9_6, kernel-64k-core 5.14.0-570.140.1.el9_6, +32 more
    fixed: vendor fix RHSA-2026:65708
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.45.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.45.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.45.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.45.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.45.1.el9_8
    fixed: vendor fix RHSA-2026:64808
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.52.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.52.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.52.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.52.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.52.1.el10_2
    fixed: vendor fix RHSA-2026:64775
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.104.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.104.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.104.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.104.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.104.1.el10_0
    fixed: vendor fix RHSA-2026:67114
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.45.1.el9_8, kernel-rt-64k 5.14.0-687.45.1.el9_8, kernel-rt-core 5.14.0-687.45.1.el9_8, kernel-rt-modules 5.14.0-687.45.1.el9_8, kernel-rt-64k-core 5.14.0-687.45.1.el9_8, kernel-rt-debug-core 5.14.0-687.45.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:64808
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.52.1.el10_2, kernel-rt-64k 6.12.0-211.52.1.el10_2, kernel-rt-core 6.12.0-211.52.1.el10_2, kernel-rt-modules 6.12.0-211.52.1.el10_2, kernel-rt-64k-core 6.12.0-211.52.1.el10_2, kernel-rt-debug-core 6.12.0-211.52.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:64775
  • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.150.1.el9_4, kernel-rt-core 5.14.0-427.150.1.el9_4, kernel-rt-modules 5.14.0-427.150.1.el9_4, kernel-rt-debug-core 5.14.0-427.150.1.el9_4, kernel-rt-modules-core 5.14.0-427.150.1.el9_4, kernel-rt-debug-modules 5.14.0-427.150.1.el9_4, +4 more
    fixed: vendor fix RHSA-2026:68100
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.104.1.el10_0, kernel-rt-64k 6.12.0-55.104.1.el10_0, kernel-rt-core 6.12.0-55.104.1.el10_0, kernel-rt-modules 6.12.0-55.104.1.el10_0, kernel-rt-64k-core 6.12.0-55.104.1.el10_0, kernel-rt-debug-core 6.12.0-55.104.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:67114
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.140.1.el9_6, kernel-rt-64k 5.14.0-570.140.1.el9_6, kernel-rt-core 5.14.0-570.140.1.el9_6, kernel-rt-modules 5.14.0-570.140.1.el9_6, kernel-rt-64k-core 5.14.0-570.140.1.el9_6, kernel-rt-debug-core 5.14.0-570.140.1.el9_6, +14 more
    fixed: vendor fix RHSA-2026:65708
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.45.1.el9_8, kernel-rt-core 5.14.0-687.45.1.el9_8, kernel-rt-modules 5.14.0-687.45.1.el9_8, kernel-rt-debug-core 5.14.0-687.45.1.el9_8, kernel-rt-modules-core 5.14.0-687.45.1.el9_8, kernel-rt-debug-modules 5.14.0-687.45.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:64808
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.52.1.el10_2, kernel-rt-core 6.12.0-211.52.1.el10_2, kernel-rt-modules 6.12.0-211.52.1.el10_2, kernel-rt-debug-core 6.12.0-211.52.1.el10_2, kernel-rt-modules-core 6.12.0-211.52.1.el10_2, kernel-rt-debug-modules 6.12.0-211.52.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:64775
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.150.1.el9_4, kernel-rt-kvm 5.14.0-427.150.1.el9_4, kernel-rt-core 5.14.0-427.150.1.el9_4, kernel-rt-modules 5.14.0-427.150.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.150.1.el9_4, kernel-rt-debug-core 5.14.0-427.150.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:68100
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.104.1.el10_0, kernel-rt-kvm 6.12.0-55.104.1.el10_0, kernel-rt-core 6.12.0-55.104.1.el10_0, kernel-rt-modules 6.12.0-55.104.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.104.1.el10_0, kernel-rt-debug-core 6.12.0-55.104.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:67114
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.140.1.el9_6, kernel-rt-kvm 5.14.0-570.140.1.el9_6, kernel-rt-core 5.14.0-570.140.1.el9_6, kernel-rt-modules 5.14.0-570.140.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.140.1.el9_6, kernel-rt-debug-core 5.14.0-570.140.1.el9_6, +6 more
    fixed: vendor fix RHSA-2026:65708
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-26-295-11 updated cvss 7.8

Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.7 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.7
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
  • CWE-835 Loop with Unreachable Exit Condition
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.