VulnerabilityPublished 18 Jun 2025Updated 5 Nov 2026

CVE-2025-38063: Linux kernel · dm: fix unconditional IO throttle caused by REQ_PREFLUSH

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in b55a97d1bd4083729a60d19beffe85d4c96680de : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:19 UTC

Severity

Unrated

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

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in b55a97d1bd4083729a60d19beffe85d4c96680de, 2858cda9a8d95e6deee7e3b0a26adde696a9a4f5, 95d08924335f3b6f4ea0b92ebfe4fe0731c502d9 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 5 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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
LinuxLinux	Affected ≥ e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c, < b55a97d1bd4083729a60d19beffe85d4c96680de	Fixed in b55a97d1bd4083729a60d19beffe85d4c96680de
LinuxLinux	Affected ≥ e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c, < 2858cda9a8d95e6deee7e3b0a26adde696a9a4f5	Fixed in 2858cda9a8d95e6deee7e3b0a26adde696a9a4f5
LinuxLinux	Affected ≥ e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c, < 95d08924335f3b6f4ea0b92ebfe4fe0731c502d9	Fixed in 95d08924335f3b6f4ea0b92ebfe4fe0731c502d9
LinuxLinux	Affected ≥ e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c, < 88f7f56d16f568f19e1a695af34a7f4a6ce537a6	Fixed in 88f7f56d16f568f19e1a695af34a7f4a6ce537a6
LinuxLinux	Affected ≥ e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c, < 52aa28f7b1708d76e315d78b5ed397932a1a97c3	Fixed in 52aa28f7b1708d76e315d78b5ed397932a1a97c3
LinuxLinux	Affected =4.10	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: dm: fix unconditional IO throttle caused by REQ_PREFLUSH When a bio with REQ_PREFLUSH is submitted to dm, __send_empty_flush() generates a flush_bio with REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC, which causes the flush_bio to be throttled by wbt_wait(). An example from v5.4, similar problem also exists in upstream: crash> bt 2091206 PID: 2091206 TASK: ffff2050df92a300 CPU: 109 COMMAND: "kworker/u260:0" #0 [ffff800084a2f7f0] __switch_to at ffff80004008aeb8 #1 [ffff800084a2f820] __schedule at ffff800040bfa0c4 #2 [ffff800084a2f880] schedule at ffff800040bfa4b4 #3 [ffff800084a2f8a0] io_schedule at ffff800040bfa9c4 #4 [ffff800084a2f8c0] rq_qos_wait at ffff8000405925bc #5 [ffff800084a2f940] wbt_wait at ffff8000405bb3a0 #6 [ffff800084a2f9a0] __rq_qos_throttle at ffff800040592254 #7 [ffff800084a2f9c0] blk_mq_make_request at ffff80004057cf38 #8 [ffff800084a2fa60] generic_make_request at ffff800040570138 #9 [ffff800084a2fae0] submit_bio at ffff8000405703b4 #10 [ffff800084a2fb50] xlog_write_iclog at ffff800001280834 [xfs] #11 [ffff800084a2fbb0] xlog_sync at ffff800001280c3c [xfs] #12 [ffff800084a2fbf0] xlog_state_release_iclog at ffff800001280df4 [xfs] #13 [ffff800084a2fc10] xlog_write at ffff80000128203c [xfs] #14 [ffff800084a2fcd0] xlog_cil_push at ffff8000012846dc [xfs] #15 [ffff800084a2fda0] xlog_cil_push_work at ffff800001284a2c [xfs] #16 [ffff800084a2fdb0] process_one_work at ffff800040111d08 #17 [ffff800084a2fe00] worker_thread at ffff8000401121cc #18 [ffff800084a2fe70] kthread at ffff800040118de4 After commit 2def2845cc33 ("xfs: don't allow log IO to be throttled"), the metadata submitted by xlog_write_iclog() should not be throttled. But due to the existence of the dm layer, throttling flush_bio indirectly causes the metadata bio to be throttled. Fix this by conditionally adding REQ_IDLE to flush_bio.bi_opf, which makes wbt_should_throttle() return false to avoid wbt_wait().

References

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