Vulnerability in Linux kernel (CVE-2026-89508)
Summary
Vulnerability in Linux kernel (CVE-2026-89508). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
RDMA/ucma: Lock the handler in ucma_set_ib_path()
ucma_set_ib_path() calls ucma_event_handler() straight from the write()
path, without the handler lock that keeps ctx->file stable while a uevent
is queued. The handler re-reads ctx->file for every dereference:
mutex_lock(&ctx->file->mut); /* file A */
list_add_tail(&uevent->list, &ctx->file->event_list); /* file B */
mutex_unlock(&ctx->file->mut); /* file B */
wake_up_interruptible(&ctx->file->poll_wait); /* file B */
A concurrent ucma_migrate_id() reassigns ctx->file while the SET_OPTION
caller sleeps in mutex_lock(), so the list_add_tail() lands on file B's
event_list while only file A's mutex is held, racing every other user of
that list:
BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x1aa/0x1c0
Read of size 8 at addr ffff888153c6a418 by task poc_corr/486
Call Trace:
__list_add_valid_or_report+0x1aa/0x1c0
ucma_event_handler+0x1be/0xc00
ucma_set_ib_path+0x45e/0x710
ucma_set_option+0x32e/0x590
ucma_write+0x1f9/0x330
Allocated by task 505:
ucma_write_cm_event+0x1a1/0x660
Freed by task 505:
kfree+0x1da/0x4c0
ucma_get_event+0x5d5/0x7e0
The freed object is a ucma_event that another thread dequeued from file B's
list under file B's mutex. File A's mut is left held on top of that,
wedging its next writer in uninterruptible sleep.
This path needs a bound and address-resolved cm_id, so it requires an…
Source: NIST National Vulnerability Database NVD GitHub Advisory
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-2026-89508 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89508" on the vendor's site.
CVE-2026-89508 (Linux kernel) — CVSS v3 7.8
Attack vector: local / no user interaction
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 Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
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. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-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
- Debian DEBIAN-CVE-2026-89508 linux Fixed in: 6.1.190-1
- Ubuntu UBUNTU-CVE-2026-89508 linux-aws
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com