Unknown

CVE-2026-89732 — usb: gadget: f_fs: Prevent deadlock during ep0 read loop

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-evaluate the state machine. By not sleeping with ffs->mutex held, we natively decouple gadget teardowns (which require the mutex) from userspace polling.

Published Sep 11, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.23%

ahead of 13% of scored CVEs · Oct 21, 2026

Affects

Linux

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < fbe3db4b650c284df8eb4cb68eebcf270cf861b5≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < 30430509c156e1df2bdafd5f1cadb160e53db5d6≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < bafddd0f20b5228760be303aa69c58502e92309c≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < b0a6bfac0c3c3edf5b2ecaee87a09234601fe78d≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < fd20cc68bbdb5620696ac108e8f2efd180fe2c1a≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < 34e88f53614640b59039a46717fb6142e9871022≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < eac233e63f9db82ba874e3cccafaafab162999e0≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0 and < 569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082 and 1 more version 2.6.35	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 21, 2026 · 6 reading(s) · max 0.23%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 11, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× References added · Oct 19, 2026 – Oct 19, 2026
1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

10 on the record

git.kernel.org/stable/c/b0a6bfac0c3c3edf5b2ecaee87a09234601fe78d
NIST National Vulnerability Database
git.kernel.org/stable/c/eac233e63f9db82ba874e3cccafaafab162999e0
NIST National Vulnerability Database
git.kernel.org/stable/c/30430509c156e1df2bdafd5f1cadb160e53db5d6
NIST National Vulnerability Database
github.com/advisories/GHSA-95m6-h3qf-8pc2
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2026-89732
GitHub Security Advisories
git.kernel.org/stable/c/569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082
NIST National Vulnerability Database
git.kernel.org/stable/c/bafddd0f20b5228760be303aa69c58502e92309c
NIST National Vulnerability Database
git.kernel.org/stable/c/fbe3db4b650c284df8eb4cb68eebcf270cf861b5
NIST National Vulnerability Database
git.kernel.org/stable/c/fd20cc68bbdb5620696ac108e8f2efd180fe2c1a
NIST National Vulnerability Database
git.kernel.org/stable/c/34e88f53614640b59039a46717fb6142e9871022
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Unknown CVE-2026-98869 bpf: Infer zext_dst based on static register liveness analysis 1d
Unknown CVE-2023-7356 Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID 1d
Unknown CVE-2026-98866 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF 4d
Unknown CVE-2026-98867 dm-pcache: bound the logical key offset from persistent memory 4d
Unknown CVE-2026-98868 dm-pcache: reject a kset that overruns its segment 4d
Unknown CVE-2026-98856 kprobes: Skip disarmed probes when checking optkprobe overlap 4d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-89732 is "usb: gadget: f_fs: Prevent deadlock during ep0 read loop", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.23% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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