ubuntu-cve-2026-54904
Vulnerability from osv_ubuntu
Published
2026-06-24 17:17
Modified
2026-06-29 11:36
Summary
Details
concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReference#update can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReference#update, which retries until compare_and_set(old_value, new_value) succeeds; Numeric compare_and_set, which checks old == old_value before attempting the underlying atomic swap.; and Ruby NaN semantics, where Float::NAN == Float::NAN is always false. As a result, once an AtomicReference contains Float::NAN, calling #update repeatedly evaluates the caller's block and never returns. In services that store externally derived numeric values in an AtomicReference, this can cause CPU exhaustion or permanent request/job hangs. This vulnerability is fixed in 1.3.7.
Severity
7.5 (High)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-concurrent",
"binary_version": "1.0.0-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:16.04:LTS",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.0.0-1?arch=source\u0026distro=xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.0-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-concurrent",
"binary_version": "1.0.5-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.0.5-1?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.5-1"
]
},
{
"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"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.1.6+dfsg-3?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"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-4"
},
{
"binary_name": "ruby-concurrent-ext",
"binary_version": "1.1.6+dfsg-4"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.1.6+dfsg-4?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.6+dfsg-3",
"1.1.6+dfsg-3build1",
"1.1.6+dfsg-4"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-concurrent",
"binary_version": "1.2.3-2build1"
},
{
"binary_name": "ruby-concurrent-ext",
"binary_version": "1.2.3-2build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.2.3-2build1?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.6+dfsg-5build2",
"1.1.6+dfsg-5build3",
"1.2.3-2build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-concurrent",
"binary_version": "1.3.4-1"
},
{
"binary_name": "ruby-concurrent-ext",
"binary_version": "1.3.4-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:25.10",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.3.4-1?arch=source\u0026distro=questing"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.3.4-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-concurrent",
"binary_version": "1.3.6-1"
},
{
"binary_name": "ruby-concurrent-ext",
"binary_version": "1.3.6-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "ruby-concurrent",
"purl": "pkg:deb/ubuntu/ruby-concurrent@1.3.6-1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.3.4-1",
"1.3.6-1"
]
}
],
"aliases": [],
"details": "concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReference#update can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReference#update, which retries until compare_and_set(old_value, new_value) succeeds; Numeric compare_and_set, which checks old == old_value before attempting the underlying atomic swap.; and Ruby NaN semantics, where Float::NAN == Float::NAN is always false. As a result, once an AtomicReference contains Float::NAN, calling #update repeatedly evaluates the caller\u0027s block and never returns. In services that store externally derived numeric values in an AtomicReference, this can cause CPU exhaustion or permanent request/job hangs. This vulnerability is fixed in 1.3.7.",
"id": "UBUNTU-CVE-2026-54904",
"modified": "2026-06-29T11:36:36Z",
"published": "2026-06-24T17:17:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-54904"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-54904"
},
{
"type": "REPORT",
"url": "https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-54904"
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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