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CVE Record

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

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.

HighCVSS 7.6Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-27970 is an Angular i18n XSS issue. A malicious or compromised translation file can cause JavaScript to run in the application’s origin when affected ICU messages render. This matters most for apps using external translation workflows because the trust boundary may include contractors or localization systems.

Executive priority

Prioritize remediation for customer-facing or authentication-heavy Angular apps using outsourced localization. The issue is high severity, but exploitation is gated by translation-file compromise rather than ordinary user input.

Technical view

Affected Angular versions mishandle sanitization of HTML in translated ICU messages in the i18n pipeline. If a compromised xliff, xtb, or similar translation is merged and rendered, attacker-controlled JavaScript may execute as the application. Sources classify this as CWE-79 with CVSS 4.0 score 7.6.

Likely exposure

Exposure is likely limited to Angular applications using Angular i18n, ICU messages, and affected Angular versions, especially where translations are received from third parties. Apps with strict CSP and Trusted Types may have reduced practical impact.

Exploitation context

The bundle does not show KEV listing or confirmed active exploitation. Exploitation requires compromise of the application’s translation file before deployment or build integration, then rendering of the affected translated ICU message in a vulnerable Angular application.

Researcher notes

The source bundle names fixed releases but has a discrepancy between 21.1.16 and 21.1.6. Validate against the Angular advisory before closing findings. Do not assume all Angular apps are exposed; the i18n and ICU-message preconditions are central.

Mitigation direction

  • Upgrade affected Angular applications to vendor-fixed releases from the Angular advisory.
  • Verify the correct 21.1.x fixed version because the supplied bundle contains inconsistent version text.
  • Review translated content from untrusted third parties before incorporation.
  • Enable strict CSP controls to block unauthorized JavaScript execution.
  • Enable Trusted Types where supported to enforce safer HTML handling.

Validation and detection

  • Inventory Angular versions across applications and build artifacts.
  • Identify apps using Angular i18n and rendered ICU messages.
  • Review localization pipelines for third-party translation inputs or writable translation stores.
  • Check whether strict CSP and Trusted Types are enforced in production.
  • Confirm translation files were not unexpectedly modified before builds.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-79: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2026-27970 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.6 (4.0)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.6CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N——GitHub_M
7.1CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L1.65.5redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

7.6High
CVSS 4.0 vector shape for CVE-2026-27970Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADP@angular/core: Angular: Cross-site scripting via compromised translation files
other:Red Hat severity ratingcvssV3_1
  • 2026-02-26T03:01:37.601Z: Reported to Red Hat.
  • 2026-02-26T02:03:43.811Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
angularangular>= 21.2.0-next.0, < 21.2.0, >= 21.0.0-next.0, < 21.1.6, >= 20.0.0-next.0, < 20.3.17, >= 19.0.0-next.0, < 19.2.19, <= 18.2.14Listed
Weakness

CWE details

CWE-79

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-79 · source CWE mapping

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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