CVE-2026-89738usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed
- 7.8HighCVSS base score
- 0.19%Exploitation in 30 daysEPSS · top 91% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed In polled-VBUS mode (board.vbus_pin && board.vbus_polled), probe arms a self-restarting cycle: at91_vbus_timer() schedules vbus_timer_work, and at91_vbus_timer_work() calls at91_vbus_update() and re-arms the timer via mod_timer(). Both recover the same udc through container_of and dereference it on every iteration. Neither teardown path cancels this cycle. udc is devm-allocated, so it is freed after at91udc_remove() returns, and is likewise freed when probe fails and devres runs. A timer callback or work item that is pending or running at either point dereferences the freed udc. Add at91_udc_shutdown_vbus_timer() and call it from at91udc_remove() and from the usb_add_gadget_udc() failure path in probe; the remaining probe error paths fail before the timer is armed. timer_shutdown_sync() waits for a running callback and clears timer->function, which makes the work handler's mod_timer() a permanent no-op; cancel_work_sync() then drains any pending or running work whose re-arm attempt now does nothing. The timer must be shut down first, since cancelling the work alone would let the timer re-queue it. The guard mirrors probe: in IRQ mode the timer and work_struct are never initialized. This does not require a fault; a normal driver unbind can interleave with an already queued work item. This issue was found by an in-house static analysis tool.
Timeline
ID reserved
By Linux
Published
- 49 days later
· 49 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.19% · top 91% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < 2440ce54b8c4c8aa6963c181eb56164a466fbe1c
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < 1674e34fe61ad3f5585dc833ba6bb6522912e6a5
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < 723d73b245843d4fff4c3f42e857c78c2b2d414e
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < a2a602cb1e28d76a5398cec3fa21b0110385f501
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < 51a311eb97e91ce1aed3005cb71ccb2e30f8cce8
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < 557ef547d49ff5e6026a4d39bdd3113bd81d7688
- affected 4037242c4f5ff77afe61bf07ca1e8a99490219e5 – < c27d13ce4bab80fbdf6523928071b6c24b37606c
- affected 2.6.36
- unaffected < 2.6.36
- unaffected 5.15.224 – ≤ 5.15.*
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.109 – ≤ 6.12.*
- unaffected 6.18.50 – ≤ 6.18.*
- unaffected 7.2.4 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References7
- https://git.kernel.org/stable/c/2440ce54b8c4c8aa6963c181eb56164a466fbe1c (opens in a new tab)
- https://git.kernel.org/stable/c/1674e34fe61ad3f5585dc833ba6bb6522912e6a5 (opens in a new tab)
- https://git.kernel.org/stable/c/723d73b245843d4fff4c3f42e857c78c2b2d414e (opens in a new tab)
- https://git.kernel.org/stable/c/a2a602cb1e28d76a5398cec3fa21b0110385f501 (opens in a new tab)
- https://git.kernel.org/stable/c/51a311eb97e91ce1aed3005cb71ccb2e30f8cce8 (opens in a new tab)
- https://git.kernel.org/stable/c/557ef547d49ff5e6026a4d39bdd3113bd81d7688 (opens in a new tab)
- https://git.kernel.org/stable/c/c27d13ce4bab80fbdf6523928071b6c24b37606c (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-76650 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-89738)Record last updated .