CVE-2025-39999

Kernel panic via stale blk-mq tag pointer

Published Oct 15, 2025 · Updated May 23, 2026

Double-free in the Linux kernel 6.16.4 through 6.16.10 and 6.17 allows local users to trigger a kernel panic via nr_requests. When blk_mq_tag_update_depth replaces hctx->sched_tags after the queue depth grows, elevator->et->tags retains the freed allocation and elevator exit frees it again. Reaching the fault requires write access to a block queue's nr_requests sysfs attribute and an enabled I/O scheduler; the resulting panic interrupts the host.

CVSS severityUnavailable
Unscored
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double-free in the Linux kernel 6.16.4 through 6.16.10 and 6.17 allows local users to trigger a kernel panic via nr_requests. When blk_mq_tag_update_depth replaces hctx->sched_tags after the queue depth grows, elevator->et->tags retains the freed allocation and elevator exit frees it again. Reaching the fault requires write access to a block queue's nr_requests sysfs attribute and an enabled I/O scheduler; the resulting panic interrupts the host.

The record

CVE
CVE-2025-39999
Published
Oct 15, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1529
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 15, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=58567d8e95c096ad234963df90a2ca518901f4b6 <8faee580d63bc2a54a59dcdb7f9ce4de29384fec
  2. Affected versionversion=6.16.4 <6.16.11
  3. Affected versionversion=6.17
  4. Affected versionversion=f5a6604f7a4405450e4a1f54e5430f47290c500f <392b1d64911f4de8887fe8b68299fa8bd6e5b923
  5. Affected versionversion=f5a6604f7a4405450e4a1f54e5430f47290c500f <ba28afbd9eff2a6370f23ef4e6a036ab0cfda409

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=58567d8e95c096ad234963df90a2ca518901f4b6 <8faee580d63bc2a54a59dcdb7f9ce4de29384fec; version=6.16.4 <6.16.11; version=6.17; version=f5a6604f7a4405450e4a1f54e5430f47290c500f <392b1d64911f4de8887fe8b68299fa8bd6e5b923; version=f5a6604f7a4405450e4a1f54e5430f47290c500f <ba28afbd9eff2a6370f23ef4e6a036ab0cfda409

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1529System Shutdown/Reboot

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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