VulnerabilityPublished 15 Oct 2025Updated 9 Sep 2026

CVE-2025-39999: Linux kernel · blk-mq: fix blk_mq_tags double free while nr_requests grown

Affects Linux kernelSource GCVE Database

Not known to be exploited · fixed in 6.17.0-6.6 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Low

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.17.0-6.6, 6.17.0-1003.3, 6.17.0-1006.6 +3

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
Ubuntu 25.10linux`pkg:deb/ubuntu/linux?arch=source&distro=questing`Other threats	Affected <6.17.0-6.6	Fixed in 6.17.0-6.6
Ubuntu 25.10linux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=questing`Other threats	Affected <6.17.0-1003.3	Fixed in 6.17.0-1003.3
Ubuntu 25.10linux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=questing`Other threats	Affected <6.17.0-1006.6	Fixed in 6.17.0-1006.6
Ubuntu 25.10linux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questing`Other threats	Affected 6.17.0-1003.3 – 6.17.0-1017.17 10 affected builds	Fixed in–
Ubuntu 25.10linux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=questing`Other threats	Affected <6.17.0-1003.3	Fixed in 6.17.0-1003.3
Ubuntu 25.10linux-oracle`pkg:deb/ubuntu/linux-oracle?arch=source&distro=questing`Other threats	Affected <6.17.0-1003.3	Fixed in 6.17.0-1003.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

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/

References

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