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CVE-2026-89732

Vulnerability in Linux kernel (CVE-2026-89732)

Summary

Vulnerability in Linux kernel (CVE-2026-89732). Risk of unauthorized operations or information disclosure. Exploitable via retry.

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: f_fs: Prevent deadlock during ep0 read loop

Currently, ffs_ep0_read() holds ffs->mutex when it prepares to go to
sleep waiting for an event. When no setup events are pending, it calls
wait_event_interruptible_exclusive_locked_irq() with the mutex still
held. The wait macro deliberately drops the waitqueue spinlock before
sleeping but does not drop the mutex.

If a userspace daemon is polling ep0 via read() and the gadget is
asynchronously torn down via configfs (e.g., echo "" > UDC), a
deadlock can occur:

  1. The configfs teardown calls functionfs_unbind(), which queues a
    FUNCTIONFS_UNBIND event.
  2. The daemon wakes up, consumes the event, and drops the mutex.
  3. However, if the daemon loops and immediately issues another read()
    before exiting, it reacquires ffs->mutex and again goes into an
    interruptible sleep.
  4. Meanwhile, functionfs_unbind() continues execution and attempts to
    acquire ffs->mutex to tear down ep0req.
  5. The kernel deadlocks because the configfs thread is stuck in an
    uninterruptible sleep waiting for the mutex, while the userspace
    daemon is in an interruptible sleep holding the mutex forever
    because no more events will arrive.

To fix this, we drop both the waitqueue spinlock and ffs->mutex before
going to sleep, and use wait_event_interruptible_exclusive() instead.
Upon waking up, we jump back to the retry label to safely reacquire
the mutex and re-eva…

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-2026-89732 has been found in Linux kernel.
Attackers can target a specific entry point like retry over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89732" on the vendor's site.

CVE-2026-89732 (Linux kernel)
Attack surface: retry
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.

❓ What is the problem

A vulnerability (unclassified) exists in Linux kernel. Attackers reach the vulnerable code path via retry.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux kernel. Attack surface: retry.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Post-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。

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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