VulnerabilityPublished 18 Oct 2026Updated 21 Oct 2026

CVE-2026-98771: Linux kernel · usb: storage: sierra_ms: reject short SWoC info transfers

Source GCVE Database

Authoritative record:CVE-2026-98771

Not known to be exploited · fixed in e2d62928f2666a2964a23b1d39e6e762f0628d7b : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e2d62928f2666a2964a23b1d39e6e762f0628d7b, db9d3be156baca6ef80ae5d93acfeb85c61a74dd, c85e8331d298b8f1dee8fe63718e76435cec7133 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-7hw4-87pj-mc7h

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 32fe5e393455d87db4988af03915634304870fb4, < e2d62928f2666a2964a23b1d39e6e762f0628d7b	Fixed in e2d62928f2666a2964a23b1d39e6e762f0628d7b
LinuxLinux	Affected ≥ 32fe5e393455d87db4988af03915634304870fb4, < db9d3be156baca6ef80ae5d93acfeb85c61a74dd	Fixed in db9d3be156baca6ef80ae5d93acfeb85c61a74dd
LinuxLinux	Affected ≥ 32fe5e393455d87db4988af03915634304870fb4, < c85e8331d298b8f1dee8fe63718e76435cec7133	Fixed in c85e8331d298b8f1dee8fe63718e76435cec7133
LinuxLinux	Affected ≥ 32fe5e393455d87db4988af03915634304870fb4, < 8a0200d14acd9db388b85cd016e68a4e60d900ec	Fixed in 8a0200d14acd9db388b85cd016e68a4e60d900ec
LinuxLinux	Affected ≥ 32fe5e393455d87db4988af03915634304870fb4, < 4faaad69f18332246bbd4ca41718beb2a305bb72	Fixed in 4faaad69f18332246bbd4ca41718beb2a305bb72
LinuxLinux	Affected =2.6.27	Fixed in–

AI-suggested

A fix is available that rejects short SWoC info transfers and only accepts the full expected data size. The sierra_ms_init() function already retries failed queries, so well-behaved devices are unaffected. Users should update their Linux kernel to a version that includes this fix. Patch status is not explicitly confirmed in the provided data; check the vendor advisory or Linux kernel mailing lists for the official patch and remediation guidance.

Description

A vulnerability in the Linux kernel's usb storage driver for Sierra Wireless devices allows a malicious USB device to cause a partial information leak. The flaw occurs because the driver accepts short USB control message transfers without verifying the full expected data length, leading to uninitialized kernel memory being exposed via a sysfs attribute. This can disclose up to 5 bytes of stale kernel heap memory to unprivileged userspace per read. The issue is resolved by rejecting short transfers and only accepting full data structures.

Impact

An attacker controlling a malicious USB device can exploit this vulnerability to leak small amounts of kernel heap memory to unprivileged userspace repeatedly. This information leak could potentially aid further attacks by revealing kernel memory contents. The leak is limited to up to 5 bytes per sysfs read and only occurs if the kernel is built without init_on_alloc, which zeroes memory on allocation.

Summary

The Linux kernel's usb storage driver for Sierra Wireless devices (sierra_ms) had a vulnerability where the sierra_get_swoc_info() function requested 60 bytes from the device but only treated negative return values as failures. If a malicious device responded with a short IN transfer, the driver accepted it, leaving the tail of the allocated swoc_info buffer uninitialized. The truinst_show() function then exposed parts of this uninitialized buffer (including rev, LinuxSKU, LinuxVer fields) via a world-readable sysfs attribute, leaking up to 5 bytes of stale kernel heap memory to unprivileged userspace. The fix ensures that only full-size transfers are accepted, preventing this information leak.

References

Community reviews

Loading reviews…