CVE-2025-21888: Linux kernel · RDMA/mlx5: Fix a WARN during dereg_mr for DM type
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 30 Oct 2026, 14:18 UTC
Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 27 Mar 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 30 Oct 2026.
What to do
AI-suggested
A fix has been implemented in the Linux kernel to properly handle DM type memory regions during deregistration, preventing the kernel warning. Users should update to a Linux kernel version that includes this fix. Since no vendor advisory or patch link is provided, confirm the fix availability in the kernel changelogs or stable releases after 6.12.0-rc7+ where this issue was identified.
Description
A warning occurs in the Linux kernel's RDMA mlx5 driver during deregistration of device memory (DM) type memory regions due to incorrect handling of DMA unmapping. This issue has been fixed by correcting the code path to properly handle DM type memory regions and avoid calling dma_unmap_single() on unmapped DMA addresses.
References
- git.kernel.org/stable/c/8fe3c674ef289cdc0760fe787e7584d805ab9301 (opens in a new tab)
- git.kernel.org/stable/c/6e59f56161cccc437d665212d5c3ea3f1c3f5a1f (opens in a new tab)
- git.kernel.org/stable/c/0bd34bdd468e93a779c403de3cf7d43ee633b3e0 (opens in a new tab)
- git.kernel.org/stable/c/f1298cad47ae29828c5c5be77e733ccfcaef6a7f (opens in a new tab)
- git.kernel.org/stable/c/abc7b3f1f056d69a8f11d6dceecc0c9549ace770 (opens in a new tab)