CVE-2026-43327USB: dummy-hcd: Fix locking/synchronization error
- 5.5MediumCVSS base score
- 0.10%Exploitation in 30 daysEPSS · top 99% 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: dummy-hcd: Fix locking/synchronization error Syzbot testing was able to provoke an addressing exception and crash in the usb_gadget_udc_reset() routine in drivers/usb/gadgets/udc/core.c, resulting from the fact that the routine was called with a second ("driver") argument of NULL. The bad caller was set_link_state() in dummy_hcd.c, and the problem arose because of a race between a USB reset and driver unbind. These sorts of races were not supposed to be possible; commit 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"), along with a few followup commits, was written specifically to prevent them. As it turns out, there are (at least) two errors remaining in the code. Another patch will address the second error; this one is concerned with the first. The error responsible for the syzbot crash occurred because the stop_activity() routine will sometimes drop and then re-acquire the dum->lock spinlock. A call to stop_activity() occurs in set_link_state() when handling an emulated USB reset, after the test of dum->ints_enabled and before the increment of dum->callback_usage. This allowed another thread (doing a driver unbind) to sneak in and grab the spinlock, and then clear dum->ints_enabled and dum->driver. Normally this other thread would have to wait for dum->callback_usage to go down to 0 before it would clear dum->driver, but in this case it didn't have to wait since dum->callback_usage had not yet been incremented. The fix is to increment dum->callback_usage _before_ calling stop_activity() instead of after. Then the thread doing the unbind will not clear dum->driver until after the call to usb_gadget_udc_reset() safely returns and dum->callback_usage has been decremented again.
Timeline
ID reserved
By Linux
- 7 days later
· 7 days later
Published
- 15 days later
· 15 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 |
|---|---|---|---|
| NVDNVD · Analyzed | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.10% · top 99% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < 6350c7dd33ab481ef41c931a238361490c32d15c
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < cc97fb5969177cccce2e23b31298df220fc7570d
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < 218886b2ef2dea7627d3700ab0abaf4bf9d1161f
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < 791966f85b439b261bf19865cf1c07c065ffb4b4
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < 805b1833d6ed6da5086e610578a28e71bb54fbbb
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < efbd9441f1e769a7aae1813d497cec09cbdff031
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < 69ab97a693251d6a6093e630060a3c744fd58524
- affected 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 – < 616a63ff495df12863692ab3f9f7b84e3fa7a66d
- affected 7b416b9dac6ede26d4ca0c1a88b448b543623ff3
- affected 8590bc1da625dd4a589eac0fc3aa3cf4f400424d
- affected a867d5b932ac4911d3f8a1e63505061b0c81f889
- affected e84b4a008365b7edbd842a063ae28d040a98db25
- affected e39b17143a5b5aac81f066d455e5d3a9877eb3ae
- affected 4f8ae1fcb0dfbb72a7678f81bf01fb7fc85c6715
- affected 3.2.97 – < 3.3
- affected 3.16.52 – < 3.17
- affected 4.1.46 – < 4.2
- affected 4.4.92 – < 4.5
- affected 4.9.55 – < 4.10
- affected 4.13.6 – < 4.14
- affected 4.14
- unaffected < 4.14
- unaffected 5.10.253 – ≤ 5.10.*
- unaffected 5.15.203 – ≤ 5.15.*
- unaffected 6.1.168 – ≤ 6.1.*
- unaffected 6.6.134 – ≤ 6.6.*
- unaffected 6.12.81 – ≤ 6.12.*
- unaffected 6.18.22 – ≤ 6.18.*
- unaffected 6.19.12 – ≤ 6.19.*
- unaffected 7.0 – ≤ *
References
References8
- https://git.kernel.org/stable/c/6350c7dd33ab481ef41c931a238361490c32d15c (opens in a new tab)
- https://git.kernel.org/stable/c/cc97fb5969177cccce2e23b31298df220fc7570d (opens in a new tab)
- https://git.kernel.org/stable/c/218886b2ef2dea7627d3700ab0abaf4bf9d1161f (opens in a new tab)
- https://git.kernel.org/stable/c/791966f85b439b261bf19865cf1c07c065ffb4b4 (opens in a new tab)
- https://git.kernel.org/stable/c/805b1833d6ed6da5086e610578a28e71bb54fbbb (opens in a new tab)
- https://git.kernel.org/stable/c/efbd9441f1e769a7aae1813d497cec09cbdff031 (opens in a new tab)
- https://git.kernel.org/stable/c/69ab97a693251d6a6093e630060a3c744fd58524 (opens in a new tab)
- https://git.kernel.org/stable/c/616a63ff495df12863692ab3f9f7b84e3fa7a66d (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-2026-28611 (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-2026-43327)Record last updated .