CVE-2025-21888: RDMA/mlx5: Fix a WARN during dereg_mr for DM type

mediumCVSS 5.5CVE-2025-21888

CSIRTS triage

vendor: Mellanox product: Linux kernel RDMA/mlx5 driverOther

What: A WARN condition occurs in deregister_mr for memory region operations of type DM.
Who is affected: Systems running Linux kernel with Mellanox InfiniBand/RDMA hardware.
Urgency: Medium severity with CVSS 5.5; not currently exploited but could trigger kernel warnings.
Action: Apply Linux kernel patch CVE-2025-21888 when available or update to a patched kernel version.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21888

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2025-218880.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2025-21888	coverage & exploitation status	NVD · CVE.org

Recent advisories for RDMA/mlx5

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-74396: In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix UMR XLT cle…nvd · 2026-08-15
unknownCVE-2026-74395: In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix devx subscr…nvd · 2026-08-15
highCVE-2026-74297: In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix undefined s…nvd · 2026-08-15
highCVE-2026-74296: In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Release the HW‑…nvd · 2026-08-15
mediumCVE-2026-45973: RDMA/mlx5: Fix UMR hang in LAG error state unloadmsrc · 2026-08-06
mediumCVE-2024-53224: RDMA/mlx5: Move events notifier registration to be after device registrationmsrc · 2026-08-06