Vulnerability in Kernel (CVE-2025-21888)
Summary
Vulnerability in Kernel (CVE-2025-21888). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.12.18, 6.13.6 or later.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
RDMA/mlx5: Fix a WARN during dereg_mr for DM type
Memory regions (MR) of type DM (device memory) do not have an associated
umem.
In the __mlx5_ib_dereg_mr() -> mlx5_free_priv_descs() flow, the code
incorrectly takes the wrong branch, attempting to call
dma_unmap_single() on a DMA address that is not mapped.
This results in a WARN [1], as shown below.
The issue is resolved by properly accounting for the DM type and
ensuring the correct branch is selected in mlx5_free_priv_descs().
[1]
WARNING: CPU: 12 PID: 1346 at drivers/iommu/dma-iommu.c:1230 iommu_dma_unmap_page+0x79/0x90
Modules linked in: ip6table_mangle ip6table_nat ip6table_filter ip6_tables iptable_mangle xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry ovelay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm mlx5_ib ib_uverbs ib_core fuse mlx5_core
CPU: 12 UID: 0 PID: 1346 Comm: ibv_rc_pingpong Not tainted 6.12.0-rc7+ #1631
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:iommu_dma_unmap_page+0x79/0x90
Code: 2b 49 3b 29 72 26 49 3b 69 08 73 20 4d 89 f0 44 89 e9 4c 89 e2 48 89 ee 48 89 df 5b 5d 41 5c 41 5d 41 5e 41 5f e9 07 b8 88 ff <0f> 0b 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 66 0f 1f 44 00
RSP: 0018:ffffc90001913a10 EFLAGS: 000102…
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2025-21888 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.12.18, 6.13.6 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-21888" on the vendor's site.
CVE-2025-21888 (Kernel)
Patched: 6.12.18, 6.13.6 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Kernel.
Check the vendor advisory for the affected versions of Kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 6.12.18, 6.13.6.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Kernel' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Kernelを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Kernel to 6.12.18, 6.13.6ステージング環境で 6.12.18, 6.13.6 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2025-21888 linux-lts
- Debian DEBIAN-CVE-2025-21888 linux
- Ubuntu UBUNTU-CVE-2025-21888 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org