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VulnerabilityPublished

CVE-2026-126352: Addressable · Regular Expression Denial of Service in templates with multiple variables

Affects addressableSource GCVE Database

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Authoritative record:CVE-2026-126352· Medium 5.9

Not known to be exploited · CVSS 5.9 Medium : upgrade to 2.9.1 when convenient.

Data as of 12 Nov 2026, 23:21 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.15.9
Patch
Available – fixed in 2.9.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Upgrade addressable to 2.9.1.

Affected software

ProductAffectedFixed in
RubyGemsaddressableAffected
  • >=2.3.0 <2.9.1
Fixed in
  • 2.9.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in Addressable version 2.9.1. Users should upgrade to this version to remediate the vulnerability. Additionally, upgrading to MRI Ruby 3.3 or later mitigates the issue due to improved regex engine memoization. If upgrading is not immediately possible, avoid matching user-supplied input against templates with multiple variables in one expression or adjacent expressions. Applying a short timeout around calls to Template#match or Template#extract that process user input can also reduce risk.

Description

Addressable versions 2.3.0 through 2.9.0 contain a Regular Expression Denial of Service (ReDoS) vulnerability in the URI template matching implementation. Templates with multiple variables in one expression or several single-variable expressions can cause excessive backtracking when matching maliciously crafted URIs, leading to high CPU consumption and denial of service. This affects Ruby implementations with backtracking regex engines such as MRI Ruby < 3.3, JRuby, and TruffleRuby 40.0. The issue is fixed in Addressable 2.9.1 and mitigated in MRI Ruby 3.3 and later.

References

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