UBUNTU-CVE-2026-54905

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Source
https://ubuntu.com/security/CVE-2026-54905
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-54905
Upstream
Published
2026-06-24T17:17:00Z
Modified
2026-06-29T13:56:54Z
Severity
  • 2.0 (Low) CVSS_V4 - CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N CVSS Calculator
  • 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReentrantReadWriteLock can incorrectly grant a write lock after one thread acquires the read lock 32,768 times. The lock stores a thread's local read and write hold counts in one integer. The low 15 bits are used for the read hold count, and bit 15 is used as WRITE_LOCK_HELD. After 32,768 reentrant read acquisitions, the local read count crosses into the write-lock bit. try_write_lock then treats the thread as already holding a write lock and returns true without setting the global RUNNING_WRITER bit. This breaks the core mutual-exclusion guarantee: the caller is told it has a write lock, but other threads can still hold or acquire read locks at the same time. This vulnerability is fixed in 1.3.7.

References

Affected packages

Ubuntu:16.04:LTS
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.0.0-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.0.0-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"
Ubuntu:18.04:LTS
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.0.5-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.0.5-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"
Ubuntu:20.04:LTS
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.0.5-3
1.0.5-4
1.1.6+dfsg-2
1.1.6+dfsg-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.1.6+dfsg-3"
        },
        {
            "binary_name": "ruby-concurrent-ext",
            "binary_version": "1.1.6+dfsg-3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"
Ubuntu:22.04:LTS
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.1.6+dfsg-3
1.1.6+dfsg-3build1
1.1.6+dfsg-4

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.1.6+dfsg-4"
        },
        {
            "binary_name": "ruby-concurrent-ext",
            "binary_version": "1.1.6+dfsg-4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"
Ubuntu:24.04:LTS
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.1.6+dfsg-5build2
1.1.6+dfsg-5build3
1.2.3-2build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.2.3-2build1"
        },
        {
            "binary_name": "ruby-concurrent-ext",
            "binary_version": "1.2.3-2build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"
Ubuntu:25.10
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.3.4-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.3.4-1"
        },
        {
            "binary_name": "ruby-concurrent-ext",
            "binary_version": "1.3.4-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"
Ubuntu:26.04:LTS
ruby-concurrent

Package

Name
ruby-concurrent
Purl
pkg:deb/ubuntu/ruby-concurrent?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.3.4-1
1.3.6-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "ruby-concurrent",
            "binary_version": "1.3.6-1"
        },
        {
            "binary_name": "ruby-concurrent-ext",
            "binary_version": "1.3.6-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54905.json"