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NVD / CVE Program· CNA Linux

CVE-2026-43327: USB: dummy-hcd: Fix locking/synchronization error

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.09% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 218886b2ef2dea7627d3700ab0abaf4bf9d1161f, 3.17, 3.3.

Low priority for now. Upgrade to Linux Linux 218886b2ef2dea7627d3700ab0abaf4bf9d1161f, 3.17, 3.3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 8, 2026
Updated
Jun 17, 2026
EPSS
0.0% · 0th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.0%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel3.2.97 and later · before 3.3
  • linux linux kernel3.16.52 and later · before 3.17
  • linux linux kernel4.1.46 and later · before 4.2
  • linux linux kernel4.4.92 and later · before 4.5
  • linux linux kernel4.9.55 and later · before 4.10
  • linux linux kernel4.14 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.168
  • linux linux kernel6.2 and later · before 6.6.134
  • linux linux kernel6.7 and later · before 6.12.81
  • linux linux kernel6.13 and later · before 6.18.22
  • linux linux kernel6.19 and later · before 6.19.12
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 7b416b9dac6ede26d4ca0c1a88b448b543623ff3, 8590bc1da625dd4a589eac0fc3aa3cf4f400424d, a867d5b932ac4911d3f8a1e63505061b0c81f889, e84b4a008365b7edbd842a063ae28d040a98db25, e39b17143a5b5aac81f066d455e5d3a9877eb3ae, 4f8ae1fcb0dfbb72a7678f81bf01fb7fc85c6715, 4.14affected
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before 6350c7dd33ab481ef41c931a238361490c32d15caffected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before cc97fb5969177cccce2e23b31298df220fc7570daffected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before 218886b2ef2dea7627d3700ab0abaf4bf9d1161faffected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before 791966f85b439b261bf19865cf1c07c065ffb4b4affected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before 805b1833d6ed6da5086e610578a28e71bb54fbbbaffected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before efbd9441f1e769a7aae1813d497cec09cbdff031affected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before 69ab97a693251d6a6093e630060a3c744fd58524affected · git
    • 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81 and later · before 616a63ff495df12863692ab3f9f7b84e3fa7a66daffected · git
    • 3.2.97 and later · before 3.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.12-16.19.12-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
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  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-43324May 8, 2026 · USB: dummy-hcd: Fix interrupt synchronization error
    31Monitor
  • ← EarlierCVE-2026-43326May 8, 2026 · sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback
    22Monitor
  • Later →CVE-2026-43328May 8, 2026 · cpufreq: governor: fix double free in cpufreq_dbs_governor_init() error path
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux218886b2ef2dea7627d3700ab0abaf4bf9d1161fVendor (CNA)
Linux Linux3.17Vendor (CNA)
Linux Linux3.3Vendor (CNA)
Linux Linux4.10Vendor (CNA)
Linux Linux4.14Vendor (CNA)
Linux Linux4.2Vendor (CNA)
Linux Linux4.5Vendor (CNA)
Linux Linux616a63ff495df12863692ab3f9f7b84e3fa7a66dVendor (CNA)
Linux Linux6350c7dd33ab481ef41c931a238361490c32d15cVendor (CNA)
Linux Linux69ab97a693251d6a6093e630060a3c744fd58524Vendor (CNA)
Linux Linux791966f85b439b261bf19865cf1c07c065ffb4b4Vendor (CNA)
Linux Linux805b1833d6ed6da5086e610578a28e71bb54fbbbVendor (CNA)
Linux Linuxcc97fb5969177cccce2e23b31298df220fc7570dVendor (CNA)
Linux Linuxefbd9441f1e769a7aae1813d497cec09cbdff031Vendor (CNA)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-667 · Improper Locking

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records