| Name | CVE-2026-54904 |
| Description | 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| ruby-concurrent (PTS) | bullseye | 1.1.6+dfsg-3 | vulnerable |
| bookworm | 1.1.6+dfsg-5 | vulnerable | |
| trixie | 1.3.5-1 | vulnerable | |
| forky, sid | 1.3.8-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| ruby-concurrent | source | (unstable) | 1.3.7-1 |
[trixie] - ruby-concurrent <no-dsa> (Minor issue)
[bookworm] - ruby-concurrent <postponed> (Minor issue; requires an application to store Float::NAN in a Concurrent::AtomicReference and then call #update on it)
[bullseye] - ruby-concurrent <postponed> (Minor issue; requires an application to store Float::NAN in a Concurrent::AtomicReference and then call #update on it)
https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj