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Fencer Vulns
high 7.8

CVE-2025-38453 json

io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU

published 2025-07-25 15 mo ago modified 2026-08-05 3 mo ago also EUVD-2025-22688

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU

syzbot reports that defer/local task_work adding via msg_ring can hit a request that has been freed:

CPU: 1 UID: 0 PID: 19356 Comm: iou-wrk-19354 Not tainted 6.16.0-rc4-syzkaller-00108-g17bbde2e1716 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xd2/0x2b0 mm/kasan/report.c:521 kasan_report+0x118/0x150 mm/kasan/report.c:634 io_req_local_work_add io_uring/io_uring.c:1184 [inline] __io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1252 io_msg_remote_post io_uring/msg_ring.c:103 [inline] io_msg_data_remote io_uring/msg_ring.c:133 [inline] __io_msg_ring_data+0x820/0xaa0 io_uring/msg_ring.c:151 io_msg_ring_data io_uring/msg_ring.c:173 [inline] io_msg_ring+0x134/0xa00 io_uring/msg_ring.c:314 __io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1739 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1762 io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1874 io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:642 io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:696 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>

which is supposed to be safe with how requests are allocated. But msg ring requests alloc and free on their own, and hence must defer freeing to a sane time.

Add an rcu_head and use kfree_rcu() in both spots where requests are freed. Only the one in io_msg_tw_complete() is strictly required as it has been visible on the other ring, but use it consistently in the other spot as well.

This should not cause any other issues outside of KASAN rightfully complaining about it.

Patch / fix

  • Linux Linux 6.12.46, 6.15.7, 6.16
  • linux Debian 13 6.12.48-1
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-38453

  • linux-aws-6.14 Ubuntu 24.04 LTS 6.14.0-1017.17~24.04.1
  • linux-gcp-6.14 Ubuntu 24.04 LTS 6.14.0-1020.21~24.04.1
  • linux-oem-6.14 Ubuntu 24.04 LTS 6.14.0-1016.16
  • linux-azure-6.14 Ubuntu 24.04 LTS 6.14.0-1017.17~24.04.1
  • linux-riscv-6.14 Ubuntu 24.04 LTS 6.14.0-36.36.1~24.04.1
  • linux-oracle-6.14 Ubuntu 24.04 LTS 6.14.0-1017.17~24.04.1
  • linux-realtime-6.14 Ubuntu Pro Realtime 24.04 LTS 6.14.0-1016.16~24.04.1

ubuntu advisories UBUNTU-CVE-2025-38453

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

  • kernel RHEL 10.1 6.12.0-124.31.1.el10_1
  • rv RHEL 10.1 6.12.0-124.31.1.el10_1
  • perf RHEL 10.1 6.12.0-124.31.1.el10_1
  • rtla RHEL 10.1 6.12.0-124.31.1.el10_1
  • libperf RHEL 10.1 6.12.0-124.31.1.el10_1
  • kernel-rt RHEL 10.1 6.12.0-124.31.1.el10_1
  • kernel-64k RHEL 10.1 6.12.0-124.31.1.el10_1
  • kernel-core RHEL 10.1 6.12.0-124.31.1.el10_1

red hat advisories RHSA-2026:1727RHSA-2026:1690

  • kernel-rt Linux Micro 6.2 6.12.0-160000.6.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.6.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1.160000.2.4
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1
  • kernel-obs-qa SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.6.1
  • kernel-kvmsmall SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.6.1

suse advisories SUSE-SU-2025:21074-1SUSE-SU-2025:21139-1SUSE-SU-2026:20560-1SUSE-SU-2025:21179-1SUSE-SU-2025:4056-1SUSE-SU-2025:4001-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.6.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-kvmsmall openSUSE Leap 16.0 6.12.0-160000.6.1

opensuse advisories openSUSE-SU-2025:20081-1

  • kernel-abi-stablelists AlmaLinux 10 6.12.0-124.31.1.el10_1

almalinux advisories ALSA-2026:1690

  • kernel Rocky Linux 10 6.12.0-124.31.1.el10_1

rocky linux advisories RLSA-2026:1690

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-2025-38453 updated cvss 7.0

kernel: io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU

  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-124.31.1.el10_1, perf 6.12.0-124.31.1.el10_1, rtla 6.12.0-124.31.1.el10_1, python3-perf 6.12.0-124.31.1.el10_1, kernel-devel-matched 6.12.0-124.31.1.el10_1, kernel-64k-devel-matched 6.12.0-124.31.1.el10_1, +7 more
    fixed: vendor fix RHSA-2026:1690
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.58.1.el10_0, perf 6.12.0-55.58.1.el10_0, rtla 6.12.0-55.58.1.el10_0, python3-perf 6.12.0-55.58.1.el10_0, kernel-devel-matched 6.12.0-55.58.1.el10_0, kernel-64k-devel-matched 6.12.0-55.58.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:1727
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-124.31.1.el10_1, kernel-64k 6.12.0-124.31.1.el10_1, kernel-core 6.12.0-124.31.1.el10_1, kernel-tools 6.12.0-124.31.1.el10_1, kernel-modules 6.12.0-124.31.1.el10_1, kernel-64k-core 6.12.0-124.31.1.el10_1, +28 more
    fixed: vendor fix RHSA-2026:1690
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.58.1.el10_0, kernel-64k 6.12.0-55.58.1.el10_0, kernel-core 6.12.0-55.58.1.el10_0, kernel-tools 6.12.0-55.58.1.el10_0, kernel-modules 6.12.0-55.58.1.el10_0, kernel-64k-core 6.12.0-55.58.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:1727
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-124.31.1.el10_1, kernel-debuginfo-common-s390x 6.12.0-124.31.1.el10_1, kernel-debuginfo-common-x86_64 6.12.0-124.31.1.el10_1, kernel-debuginfo-common-aarch64 6.12.0-124.31.1.el10_1, kernel-debuginfo-common-ppc64le 6.12.0-124.31.1.el10_1
    fixed: vendor fix RHSA-2026:1690
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.58.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.58.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.58.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.58.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.58.1.el10_0
    fixed: vendor fix RHSA-2026:1727
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-124.31.1.el10_1, kernel-rt-64k 6.12.0-124.31.1.el10_1, kernel-rt-core 6.12.0-124.31.1.el10_1, kernel-rt-modules 6.12.0-124.31.1.el10_1, kernel-rt-64k-core 6.12.0-124.31.1.el10_1, kernel-rt-debug-core 6.12.0-124.31.1.el10_1, +14 more
    fixed: vendor fix RHSA-2026:1690
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.58.1.el10_0, kernel-rt-64k 6.12.0-55.58.1.el10_0, kernel-rt-core 6.12.0-55.58.1.el10_0, kernel-rt-modules 6.12.0-55.58.1.el10_0, kernel-rt-64k-core 6.12.0-55.58.1.el10_0, kernel-rt-debug-core 6.12.0-55.58.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:1727
show 3 more
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-124.31.1.el10_1, kernel-rt-core 6.12.0-124.31.1.el10_1, kernel-rt-modules 6.12.0-124.31.1.el10_1, kernel-rt-debug-core 6.12.0-124.31.1.el10_1, kernel-rt-modules-core 6.12.0-124.31.1.el10_1, kernel-rt-debug-modules 6.12.0-124.31.1.el10_1, +4 more
    fixed: vendor fix RHSA-2026:1690
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.58.1.el10_0, kernel-rt-kvm 6.12.0-55.58.1.el10_0, kernel-rt-core 6.12.0-55.58.1.el10_0, kernel-rt-modules 6.12.0-55.58.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.58.1.el10_0, kernel-rt-debug-core 6.12.0-55.58.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:1727
  • 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 rv, perf, rtla, kernel, bpftool, libperf, +83 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

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% 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
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

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.