Addressable has a Regular Expression Denial of Service in Addressable templates — CVE-2026-35611

Summary

### Impact Within the URI template implementation in Addressable, two classes of URI template generate regular expressions vulnerable to catastrophic backtracking: 1. Templates using the `*` (explode) modifier with any expansion operator (e.g., `{foo*}`, `{+var*}`, `{#var*}`, `{/var*}`, `{.var*}`, `{;var*}`, `{?var*}`, `{&var*}`) generate patterns with nested unbounded quantifiers that are O(2^n) when matched…

Product

rubygems: addressable

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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