CVE-2025-21886

RDMA task hang via leaked parent reference

Published Mar 27, 2025 · Updated May 11, 2026

Resource-management error in Linux 6.12.13 through 6.12.17 and 6.13.2 through 6.13.5 allows local users to hang an RDMA task. destroy_unused_implicit_child_mr() increments the implicit memory-region parent's reference count but fails to decrement it when free_implicit_child_mr_work() is not scheduled. Triggering the flaw requires low-privileged local access to mlx5 RDMA implicit on-demand paging; deregistering the parent leaves the calling task blocked indefinitely.

CVSS severity5.5
Medium
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

Resource-management error in Linux 6.12.13 through 6.12.17 and 6.13.2 through 6.13.5 allows local users to hang an RDMA task. destroy_unused_implicit_child_mr() increments the implicit memory-region parent's reference count but fails to decrement it when free_implicit_child_mr_work() is not scheduled. Triggering the flaw requires low-privileged local access to mlx5 RDMA implicit on-demand paging; deregistering the parent leaves the calling task blocked indefinitely.

The record

CVE
CVE-2025-21886
Published
Mar 27, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 27, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=6.12.13 <6.12.18
  2. Affected versionversion=6.13.2 <6.13.6
  3. Affected versionversion=7cc8f681f6d4ae4478ae0f60485fc768f2b450da <cb96ae783e7249e8e5a50c22952c0bb2983133df
  4. Affected versionversion=d3d930411ce390e532470194296658a960887773 <3d8c6f26893d55fab218ad086719de1fc9bb86ba
  5. Affected versionversion=edfb65dbb9ffd3102f3ff4dd21316158e56f1976 <a095ede2daca49d15e74d66d014883f2fa8bb924

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12.13 <6.12.18; version=6.13.2 <6.13.6; version=7cc8f681f6d4ae4478ae0f60485fc768f2b450da <cb96ae783e7249e8e5a50c22952c0bb2983133df; version=d3d930411ce390e532470194296658a960887773 <3d8c6f26893d55fab218ad086719de1fc9bb86ba; version=edfb65dbb9ffd3102f3ff4dd21316158e56f1976 <a095ede2daca49d15e74d66d014883f2fa8bb924

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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