EUVD-2026-39055

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.privateaddress? returns false for IPv4-mapped IPv6 addresses ::ffff:a.b.c.d corresponding to some private IPv4 addresses,...

CVE-2026-47389 Mastodon: SSRF protection bypass on older Ruby versions

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.privateaddress? returns false for IPv4-mapped IPv6 addresses ::ffff:a.b.c.d corresponding to some private IPv4 addresses,...

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-2026-54905

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-2026-54297

Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. From 1.0.0 until 1.10.6 and 2.14.3, Faraday::NestedParamsEncoder, the default nested query parameter encoder/decoder in Faraday, decodes nested query strings without enforcing a maximum nestin...

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,...

AZL-91290 CVE-2026-54905 affecting package rubygem-concurrent-ruby for versions less than 1.3.7-1

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...

AZL-91287 CVE-2026-54906 affecting package rubygem-concurrent-ruby for versions less than 1.3.7-1

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-2026-54906

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,...

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-2026-54904

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 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

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: 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

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: 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...