In the Linux kernel, the following vulnerability has been resolved:
mmc: vub300: defer reset until cmd_mutex is unlocked
vub300_cmndwork_thread() holds cmd_mutex while it sends a command and
waits for the command response. If the response wait times out,
__vub300_command_response() kills the command URBs and then synchronously
resets the USB device through usb_reset_device().
That reset path re-enters the driver through vub300_pre_reset(), which
also takes cmd_mutex. The worker therefore tries to acquire the same
mutex recursively while it is still holding it from the command path.
This issue was found by our static analysis tool and then manually
reviewed against the current tree.
The grounded PoC kept the real worker and timeout/reset carrier:
vub300_cmndwork_thread()
__vub300_command_response()
usb_lock_device_for_reset()
usb_reset_device()
vub300_pre_reset()
Lockdep reported the same-task recursive acquisition on cmd_mutex:
WARNING: possible recursive locking detected
... (&test_vub300.cmd_mutex) ... at: usb_reset_device... [vuln_msv]
... (&test_vub300.cmd_mutex) ... at: vub300_cmndwork_thread+0x12/0x20 [vuln_msv]
Workqueue: vub300_cmd_wq vub300_cmndwork_thread [vuln_msv]
* DEADLOCK *
Return a flag from __vub300_command_response() when the timeout path needs
a device reset, then perform the reset after vub300_cmndwork_thread() has
cleared the in-flight command state and dropped cmd_mutex. The reset is
still attempted before mmc_request_done(), preserving the existing request
completion ordering while avoiding the recursive lock.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
- EG Severity
- Not assessed: no CVSS publishedA missing CVSS is not a severity of zero.
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- No SSVC decision: EchelonGraph has not assessed this CVECISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the BOD 26-04 block below.
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it