CVE-2026-54906Public exploit

Lock-state corruption via unchecked release calls

Published Jun 24, 2026 · Updated Jun 24, 2026

Improper locking in concurrent-ruby before 1.3.7 allows local users to corrupt lock state through manual ReadWriteLock release calls. release_write_lock clears the global writer bit without verifying thread ownership, while release_read_lock decrements the shared counter without confirming a held read lock. Reachability requires application code to expose or misuse these manual APIs; successful calls permit overlapping writers or leave the affected lock unable to accept readers.

CVSS severity2.1
Low
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in concurrent-ruby before 1.3.7 allows local users to corrupt lock state through manual ReadWriteLock release calls. release_write_lock clears the global writer bit without verifying thread ownership, while release_read_lock decrements the shared counter without confirming a held read lock. Reachability requires application code to expose or misuse these manual APIs; successful calls permit overlapping writers or leave the affected lock unable to accept readers.

The record

CVE
CVE-2026-54906
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
ruby-concurrency
Product
concurrent-ruby
Classifications
CWE-667, CWE-414
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 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=< 1.3.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

ruby-concurrency · concurrent-rubyversion=< 1.3.7

Published CVSS scores

2.1GitHubCVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-667Improper Locking
CWE-414Missing Lock Check

Public exploit references

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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