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VulnerabilityPublished

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

Affects asciidoctorSource 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 2.0.19 when convenient.

Data as of 15 Nov 2026, 08:42 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
EPSS
0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.0.19
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 14 Nov 2026.

What to do

Upgrade asciidoctor to 2.0.19.

Affected software

ProductAffectedFixed in
Homebrewasciidoctorpkg:brew/asciidoctorOther threatsAffected
  • >=2.0.10 <2.0.19
Fixed in
  • 2.0.19

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. Alternatively, upgrading to MRI Ruby 3.3 or later also mitigates the issue due to improved regex memoization. If upgrading is not immediately possible, avoid matching user-supplied input against vulnerable templates with multiple variables or adjacent expressions. Applying a short timeout around calls to Template#match or Template#extract that process user input can also reduce risk. Users of JRuby or TruffleRuby should prioritize upgrading Addressable as runtime upgrades may not fully mitigate the issue.

Description

Addressable versions from 2.3.0 (excluding yanked 2.3.0 and 2.3.1) through 2.9.0 contain a Regular Expression Denial of Service (ReDoS) vulnerability in URI template matching. This occurs when templates use multiple variables in one expression or several single-variable expressions adjacent to each other, causing excessive backtracking in the regex engine. The vulnerability affects Ruby implementations with backtracking regex engines such as MRI Ruby before 3.3, JRuby, and TruffleRuby 40.0. It can lead to denial of service by consuming excessive CPU resources when matching crafted URIs. The issue is fixed in Addressable 2.9.1 and MRI Ruby 3.3 or later.

References

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