Critical Photon OS Security Update - PHSA-2026-5.0-0909

Updates of 'rubygem-concurrent-ruby' packages of Photon OS have been released...

CVE-2026-54905

A flaw was found in concurrent-ruby. The Concurrent::ReentrantReadWriteLock component can incorrectly grant a write lock to a thread while other threads still hold or can acquire read locks. This occurs when a thread acquires a read lock 32,768 times, causing an internal counter to incorrectly...

CVE-2026-54906

A flaw was found in concurrent-ruby, a Ruby library for managing concurrent operations. The Concurrent::ReadWriteLock component contains a synchronization issue where write locks can be released by unauthorized threads. This could allow multiple threads to write concurrently, potentially leading ...

CVE-2026-54904

A flaw was found in concurrent-ruby. A remote attacker could exploit a vulnerability in the Concurrent::AtomicReferenceupdate method, which can enter a permanent busy retry loop. This occurs when the current value is a special 'Not a Number' Float::NAN floating-point value, causing the method to...

Linux Distros Unpatched Vulnerability : CVE-2026-54905

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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...

Linux Distros Unpatched Vulnerability : CVE-2026-54904

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current...

Linux Distros Unpatched Vulnerability : CVE-2026-54906

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLockreleasewritelock does not verify that the calling thread acquir...

CVE-2026-54905

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...

CVE-2026-54904

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReferenceupdate, which retries until compareandsetoldvalue,...

CVE-2026-54906

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLockreleasewritelock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can...

UBUNTU-CVE-2026-54904

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReferenceupdate, which retries until compareandsetoldvalue,...

UBUNTU-CVE-2026-54906

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLockreleasewritelock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can...

UBUNTU-CVE-2026-54905

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...

CVE-2026-54906

Vulnerability summary (CVE-2026-54906) : In the Ruby concurrency library concurrent-ruby (ReadWriteLock), versions prior to 1.3.7 expose a synchronization bug in the public API. Specifically, release_write_lock does not verify that the calling thread owns the write lock, allowing another thread t...

CVE-2026-54906 concurrent-ruby: ReadWriteLock allows wrong-thread write release and stray read-release counter corruption

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLockreleasewritelock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can...

CVE-2026-54906

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLockreleasewritelock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can...

CVE-2026-54904 concurrent-ruby: `AtomicReference#update` livelocks when the stored value is `Float::NAN`

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReferenceupdate, which retries until compareandsetoldvalue,...

CVE-2026-54904

Technical details for CVE-2026-54904 are not publicly available in the provided documents. No affected versions, root cause, or fixes are described beyond the initial entry. Monitor for updates.

CVE-2026-54904

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReferenceupdate, which retries until compareandsetoldvalue,...

CVE-2026-54905 concurrent-ruby: `ReentrantReadWriteLock` read-count overflow grants a write lock without exclusivity

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...