CVE-2025-71108

Boot failure via unmasked UCSI connector count

Published Jan 14, 2026 · Updated Jan 14, 2026

Improper capability validation in affected Linux Kernel releases allows local users to prevent boot through malformed UCSI firmware data. The ucsi_init function trusts the reserved high bit in cap.num_connectors, then uses the inflated count when allocating and initializing connector state. Triggering requires UCSI platform firmware that sets bit 8; the documented consequence is a boot hang on affected hardware, with no reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper capability validation in affected Linux Kernel releases allows local users to prevent boot through malformed UCSI firmware data. The ucsi_init function trusts the reserved high bit in cap.num_connectors, then uses the inflated count when allocating and initializing connector state. Triggering requires UCSI platform firmware that sets bit 8; the documented consequence is a boot hang on affected hardware, with no reported data disclosure or modification.

The record

CVE
CVE-2025-71108
Published
Jan 14, 2026
Updated
Jan 14, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <132fe187e0d940f388f839fe2cde9b84106ad20d
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3042a57a8e8bce4a3100c3f6f03dc372aab24943
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <30cd2cb1abf4c4acdb1ddb468c946f68939819fb
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <914605b0de8128434eafc9582445306830748b93
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f72f97d0aee4a993a35f2496bca5efd24827235d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <132fe187e0d940f388f839fe2cde9b84106ad20d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3042a57a8e8bce4a3100c3f6f03dc372aab24943; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <30cd2cb1abf4c4acdb1ddb468c946f68939819fb; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <914605b0de8128434eafc9582445306830748b93; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f72f97d0aee4a993a35f2496bca5efd24827235d

Published CVSS scores

3.3OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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