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 · CVSS 5.5 Low · fixed in 5.15.0-1092.99~20.04.1 : update Linux kernel when convenient.
Data as of 12 Nov 2026, 19:33 UTC
Thin evidence
One scorer or none- Patch
- Available – fixed in 5.15.0-1092.99~20.04.1, 5.15.0-1096.105~20.04.1, 5.15.0-1092.101~20.04.1 +63
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation 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 12 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7514-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7522-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7764-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7766-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7767-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7774-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7774-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7774-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7775-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and included in multiple fixed Linux kernel versions (e.g., 5.15.0-1092.99~20.04.1 and later). Users should update their Linux kernel to one of the fixed versions provided by their distribution. After updating, a system reboot is required to apply the fix. No additional mitigations are necessary as the issue is resolved by the official patch.
Description
A vulnerability in the Linux kernel's RDMA mlx5 driver caused a warning during deregistration of device memory (DM) type memory regions. The issue was due to incorrect handling of DMA unmapping for DM type memory regions, leading to a WARN message in the kernel logs. This has been fixed by correcting the code path to properly handle DM type memory regions during deregistration.
References
- ubuntu.com/security/CVE-2025-21888 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21888 (opens in a new tab)
- git.kernel.org/linus/abc7b3f1f056d69a8f11d6dceecc0c9549ace770 (opens in a new tab)
- git.kernel.org/stable/c/0bd34bdd468e93a779c403de3cf7d43ee633b3e0 (opens in a new tab)
- git.kernel.org/stable/c/abc7b3f1f056d69a8f11d6dceecc0c9549ace770 (opens in a new tab)
- git.kernel.org/stable/c/f1298cad47ae29828c5c5be77e733ccfcaef6a7f (opens in a new tab)
- ubuntu.com/security/notices/USN-7514-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7522-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7764-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7766-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7767-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7774-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7774-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7774-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7775-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7776-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7779-1 (opens in a new tab)