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Fencer Vulns
no cvss —

CVE-2025-39999 json

blk-mq: fix blk_mq_tags double free while nr_requests grown

published 2025-10-15 12 mo ago modified 2026-10-19 20 d ago also EUVD-2025-34574

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

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

blk-mq: fix blk_mq_tags double free while nr_requests grown

In the case user trigger tags grow by queue sysfs attribute nr_requests, hctx->sched_tags will be freed directly and replaced with a new allocated tags, see blk_mq_tag_update_depth().

The problem is that hctx->sched_tags is from elevator->et->tags, while et->tags is still the freed tags, hence later elevator exit will try to free the tags again, causing kernel panic.

Fix this problem by replacing et->tags with new allocated tags as well.

Noted there are still some long term problems that will require some refactor to be fixed thoroughly[1].

[1] https://lore.kernel.org/all/20250815080216.410665-1-yukuai1@huaweicloud.com/

Patch / fix

  • Linux Linux 6.16.11, 6.17.1, 6.18
  • linux Debian 14 6.16.11-1

debian advisories DEBIAN-CVE-2025-39999

  • linux Ubuntu 25.10 6.17.0-6.6
  • linux-aws Ubuntu 25.10 6.17.0-1003.3
  • linux-gcp Ubuntu 25.10 6.17.0-1003.3
  • linux-azure Ubuntu 25.10 6.17.0-1006.6
  • linux-raspi Ubuntu 25.10 6.17.0-1004.4
  • linux-riscv Ubuntu 25.10 6.17.0-6.6.1
  • linux-oracle Ubuntu 25.10 6.17.0-1003.3
  • linux-realtime Ubuntu 25.10 6.17.0-1002.3

ubuntu advisories UBUNTU-CVE-2025-39999

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-source-longterm openSUSE Tumbleweed 6.18.16-1.1
  • kernel-source openSUSE Tumbleweed 6.17.5-1.1

opensuse advisories openSUSE-SU-2026:10301-1openSUSE-SU-2025:15671-1

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-2025-39999 updated cvss 5.2

kernel: blk-mq: fix blk_mq_tags double free while nr_requests grown

  • Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • 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

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

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.