CVE-2026-63988

Kernel crash via sleeping under bridge spinlock

Published Jul 19, 2026 · Updated Jul 19, 2026

Improper locking in Linux Kernel 6.15 allows local users with NET_ADMIN to crash the kernel through bridge-port sysfs writes. brport_store() holds the bridge spinlock while a flag change reaches dev_set_promiscuity(), which can sleep and triggers a BUG in atomic context. Administrative network capability and a configured bridge port are required; successful triggering interrupts the host by crashing its kernel.

CVSS severityUnavailable
Unscored
EPSS probability0.17%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in Linux Kernel 6.15 allows local users with NET_ADMIN to crash the kernel through bridge-port sysfs writes. brport_store() holds the bridge spinlock while a flag change reaches dev_set_promiscuity(), which can sleep and triggers a BUG in atomic context. Administrative network capability and a configured bridge port are required; successful triggering interrupts the host by crashing its kernel.

The record

CVE
CVE-2026-63988
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 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=6.15
  2. Affected versionversion=78cd408356fe3edbac66598772fd347bf3e32c1f <2f9cb30d97e45686f3119fff3b30f12259950910
  3. Affected versionversion=78cd408356fe3edbac66598772fd347bf3e32c1f <6d34594cc619d0d4b07d5afcad8b5984f3526dcf
  4. Affected versionversion=78cd408356fe3edbac66598772fd347bf3e32c1f <e976e3f2f2005c6267089a1a3b6344f234a59a55

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.15; version=78cd408356fe3edbac66598772fd347bf3e32c1f <2f9cb30d97e45686f3119fff3b30f12259950910; version=78cd408356fe3edbac66598772fd347bf3e32c1f <6d34594cc619d0d4b07d5afcad8b5984f3526dcf; version=78cd408356fe3edbac66598772fd347bf3e32c1f <e976e3f2f2005c6267089a1a3b6344f234a59a55

Published CVSS scores

No CVSS assessment is available in this record.

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 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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