The function _ux_host_class_storage_media_mount() is responsible for mounting partitions on a USB mass storage device.

published 2026-01-27 9 mo ago modified 2026-11-05 3 d ago also EUVD-2025-206404

cvss: 4.2; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits: 0; none known

The function _ux_host_class_storage_media_mount() is responsible for mounting partitions on a USB mass storage device. When it encounters an extended partition entry in the partition table, it recursively calls itself to mount the next logical partition.

This recursion occurs in _ux_host_class_storage_partition_read(), which parses up to four partition entries. If an extended partition is found (with type UX_HOST_CLASS_STORAGE_PARTITION_EXTENDED or EXTENDED_LBA_MAPPED), the code invokes: _ux_host_class_storage_media_mount(storage, sector + _ux_utility_long_get(...));

There is no limit on the recursion depth or tracking of visited sectors. As a result, a malicious or malformed disk image can include cyclic or excessively deep chains of extended partitions, causing the function to recurse until stack overflow occurs.

Patch / fix

fixed in 1

eclipse threadx_usbx 6.4.5.202504

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 9 mo ago (2026-01-27)

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/eclipse-threadx/usbx/security/advisories/GHSA-qfmp-wch9-rpv2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.2	CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L
NVD	3.1	7.0	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Eclipse Foundation Eclipse ThreadX - USBX

Classification

Weakness

CWE-121 Stack-based Buffer Overflow
CWE-674 Uncontrolled Recursion
CWE-787 Out-of-bounds Write

References

github.com /eclipse-threadx/usbx/security/advisories/GHSA-qfmp-wch9-rpv2
exploit, vendor-advisory

Sources

CVE List CVE-2025-55095
NVD CVE-2025-55095

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary