# CVE-2026-126350: Addressable: Regular Expression Denial of Service in Addressable templates with certain exploded expressions

Status: published. Published: 2026-11-12. Updated: 2026-11-12.

Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.3.0 until 2.9.1, URI template expressions using the explode modifier with the slash, dot, semicolon, question-mark, or ampersand operators generate ambiguous regular expressions. When Template#match or Template#extract processes an attacker-controlled URI beginning with the operator's leading character, optional member separators allow catastrophic backtracking and denial of service on MRI Ruby before 3.2 and JRuby. Addressable 2.9.0 incompletely remediated the earlier template issue because its tests did not reach these operator-prefixed paths. URI parsing and Template#expand are unaffected. This issue is fixed in version 2.9.1.

## Remediation

- fix: addressable (RubyGems): OSV reports a fixed version 2.9.1. Check the advisory for supported release branches. (source: OSV GHSA-j82w-28jv-3pmj) — https://github.com/advisories/GHSA-j82w-28jv-3pmj

## Affected products and versions

- sporkmonger / addressable: >= 2.3.0, < 2.9.1 (affected). Source: CNA: GitHub_M
-  / addressable (addressable): 2.3.2 (affected, RubyGems); 2.3.3 (affected, RubyGems); 2.3.4 (affected, RubyGems); 2.3.5 (affected, RubyGems); 2.3.6 (affected, RubyGems); 2.3.7 (affected, RubyGems); 2.3.8 (affected, RubyGems); 2.4.0 (affected, RubyGems); 2.5.0 (affected, RubyGems); 2.5.1 (affected, RubyGems); 2.5.2 (affected, RubyGems); 2.6.0 (affected, RubyGems); 2.7.0 (affected, RubyGems); 2.8.0 (affected, RubyGems); 2.8.1 (affected, RubyGems); 2.8.10 (affected, RubyGems); 2.8.2 (affected, RubyGems); 2.8.3 (affected, RubyGems); 2.8.4 (affected, RubyGems); 2.8.5 (affected, RubyGems); 2.8.6 (affected, RubyGems); 2.8.7 (affected, RubyGems); 2.8.8 (affected, RubyGems); 2.8.9 (affected, RubyGems); 2.9.0 (affected, RubyGems); Ecosystem version events: introduced 2.3.0; fixed 2.9.1. Source: OSV GHSA-j82w-28jv-3pmj

## Severity and prioritization

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: GitHub_M

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-1333

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/sporkmonger/addressable/security/advisories/GHSA-j82w-28jv-3pmj (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/sporkmonger/addressable/issues/364 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/sporkmonger/addressable/commit/26d1e9e8409a861571f9d0029022b6e9b9158b5e (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/sporkmonger/addressable/commit/26d1e9e8409a861571f9d0029022b6e9b9158b5e (security-advisories@github.com)

- https://github.com/sporkmonger/addressable/issues/364 (security-advisories@github.com)

- https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1 (security-advisories@github.com)

- https://github.com/sporkmonger/addressable/security/advisories/GHSA-j82w-28jv-3pmj (security-advisories@github.com)

- https://github.com/advisories/GHSA-j82w-28jv-3pmj (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-j82w-28jv-3pmj (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-126350; retrieved 2026-11-12; source updated 2026-11-12

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126350; retrieved 2026-11-13; source updated 2026-11-12

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-j82w-28jv-3pmj; retrieved 2026-11-12; source updated 2026-11-12

Revision: 635a286f751365c798c32dcdf1ca60385aa8cde6931aece07aacf98b8ef4fc60

Canonical: https://y2.dev/cve/CVE-2026-126350

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.