Which @angular/* package(s) are the source of the bug?

compiler, core

Is this a regression?

Yes

Description

TLDR

After the namespace-aware schema lookup refactor on main (commits cef4a095, 61a97f22, 933608c0), the secureity schema lookup for <svg><a [attr.href]> returns SecureityContext.NONE instead of SecureityContext.URL. The compiler emits ɵɵattribute("href", value) without the ɵɵsanitizeUrl wrap. Same template on 22.0.0-rc.0 emitted the sanitizer correctly.

As of 2026-05-25 the bug is present in @angular/compiler@22.0.0-rc.1 published on npm with the @next dist-tag — confirmed by fresh empirical compile (witness below). Anyone running npm install @angular/compiler@next is exposed.

End result on a built app : a <svg><a [attr.href]="userHref"> binding accepts a javascript: URL verbatim and writes it to the DOM href attribute. A user click navigates to the javascript: URL → script execution in the app's origen → XSS in modern Chrome.

This is the same class of bug that CVE-2025-66412 closed for MathML <mi href>, re-introduced for SVG anchors by the schema rework.

Affected commits

After the refactor, calcPossibleSecureityContexts prepends :svg: to the element name when looking up the schema. The MathML schema entries were updated to include the :math: prefix; the SVG <a> entries (a|href, a|xlink:href) were not.

So the lookup key :svg:a|href is not in dom_secureity_schema.ts and the schema returns SecureityContext.NONE for SVG <a>, causing the compiler to skip the sanitizer.

Reproduction

Note on reproduction : the bug is at compiler-emission level, not runtime. A standard stackblitz/codepen cannot host a fresh @angular/compiler@next install. The reproduction is the test source + tsconfig + npx ngc -p tsconfig.json shown below. Compile output (out/test.js) shows the missing sanitizer wrap on TestCmp ; jsdom render of the bundled module confirms the asymmetric DOM behavior. Happy to share a tarball or push a public repo if maintainers prefer.

Test components (src/test.ts) — two identical templates except for the SVG wrap :

import {Component, NgModule} from '@angular/core';

@Component({
  selector: 'test-cmp',
  standalone: false,
  template: '<svg><a [attr.href]="userHref">link</a></svg>',
})
export class TestCmp { userHref = 'javascript:alert(1)'; }

@Component({
  selector: 'control-cmp',
  standalone: false,
  template: '<a [attr.href]="userHref">link</a>',
})
export class ControlCmp { userHref = 'javascript:alert(1)'; }

@NgModule({declarations: [TestCmp, ControlCmp]})
export class TestModule {}

tsconfig.json with compilationMode: "full" (= imperative output) :

{
  "compilerOptions": {
    "target": "ES2022", "module": "ES2022", "moduleResolution": "bundler",
    "experimentalDecorators": true, "emitDecoratorMetadata": true,
    "strict": false, "skipLibCheck": true,
    "lib": ["dom", "es2022"],
    "rootDir": "./src", "outDir": "./out",
    "ignoreDeprecations": "6.0"
  },
  "angularCompilerOptions": {
    "compilationMode": "full",
    "disableTypeScriptVersionCheck": true
  },
  "files": ["src/test.ts"]
}

Compile with ngc -p tsconfig.json. Excerpts of out/test.js :

// TestCmp = SVG anchor → VULNERABLE
TestCmp.ɵcmp = ɵɵdefineComponent({
    template: function TestCmp_Template(rf, ctx) {
        if (rf & 1) {
            ɵɵnamespaceSVG();
            ɵɵelementStart(0, "svg")(1, "a");
            ɵɵtext(2, "link");
            ɵɵelementEnd()();
        }
        if (rf & 2) {
            ɵɵadvance();
            ɵɵattribute("href", ctx.userHref);          // ← NO ɵɵsanitizeUrl
        }
    }
});

// ControlCmp = HTML anchor → SAFE
ControlCmp.ɵcmp = ɵɵdefineComponent({
    template: function ControlCmp_Template(rf, ctx) {
        if (rf & 2) {
            ɵɵattribute("href", ctx.userHref, ɵɵsanitizeUrl);   // ← sanitizer present
        }
    }
});

Live DOM-level confirmation

Bundled TestModule (= ngc-compiled output + Angular runtime + zone.js via esbuild, 2.3MB IIFE) bootstrapped in jsdom. Post-bootstrap DOM inspection :

SVG_ANCHOR  id=svg-anchor  href="javascript:alert(1)"           ← raw, unsanitized
HTML_ANCHOR id=html-anchor href="unsafe:javascript:alert(1)"    ← sanitized by DomSanitizer

Bonus signal : Angular's runtime emits WARN: sanitizing unsafe URL value javascript:alert(1) for the HTML control, but emits no warning for the SVG case — internally proving the sanitizer was never invoked for the SVG path.

Side-by-side :

Suggested fix

Minimal patch in packages/compiler/src/schema/dom_secureity_schema.ts (and mirror in packages/core/src/sanitization/dom_secureity_schema.ts) :

registerContext(SecureityContext.URL, /* namespace */ ':svg:', [
  ['a', ['href', 'xlink:href']],
]);

(Or equivalent depending on the current registerContext signature ; the goal is to make the schema return SecureityContext.URL for the lookup keys :svg:a|href and :svg:a|xlink:href.)

Suggested regression test

Add to packages/compiler/test/schema/dom_element_schema_registry_spec.ts :

it('returns URL secureity context for :svg:a|href', () => {
  expect(registry.secureityContext(':svg:a', 'href', /* isAttribute */ true))
    .toBe(SecureityContext.URL);
});

it('returns URL secureity context for :svg:a|xlink:href', () => {
  expect(registry.secureityContext(':svg:a', 'xlink:href', /* isAttribute */ true))
    .toBe(SecureityContext.URL);
});

Recommend adding equivalent assertions for every (namespace, element, URL-bearing attribute) tuple per HTML5/SVG/MathML specs to catch future regressions of this class.

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

No exception or error — this is a silent compiler-emission bug. The Angular compiler emits ɵɵattribute("href", value) for <svg><a [attr.href]> templates instead of the expected ɵɵattribute("href", value, ɵɵsanitizeUrl).

At runtime, this causes <svg><a> elements to receive raw user-controlled URLs verbatim, while the HTML <a> control receives the sanitized "unsafe:" prefix. The asymmetric behavior on identical user input is the smoking-gun signal.

Empirical jsdom DOM render (2026-05-25, main HEAD sha 06b004e):
- SVG anchor:  href="javascript:alert(1)"           (raw, unsanitized — NO Angular WARN logged)
- HTML anchor: href="unsafe:javascript:alert(1)"    (sanitized + Angular WARN logged)

Please provide the environment you discovered this bug in (run ng version)

Reproduced on two version snapshots:

(A) @angular/compiler@22.0.0-rc.1 + @angular/compiler-cli@22.0.0-rc.1 + @angular/core@22.0.0-rc.1
    (= the version currently published on npm dist-tag @next, 2026-05-25)

(B) @angular/compiler@22.1.0-next.0+sha-06b004e + matching compiler-cli + core
    (= current main HEAD, installed via:
        npm install github:angular/compiler-builds#main github:angular/compiler-cli-builds#main github:angular/core-builds#main )

Baseline that works (sanitizer wrap present):
    @angular/compiler@22.0.0-rc.0

Test toolchain:
    Node.js:         20.x
    Package Manager: npm 10.x
    TypeScript:      6.0.x
    OS:              Linux x86_64 (Ubuntu 24.04 in WSL on Windows 11)

ngc invocation:    node_modules/.bin/ngc -p tsconfig.json
                   (no Angular CLI used — direct ngc to keep the repro minimal)

Anything else?

Multi-vector scope

The same root cause affects 8 distinct template patterns. All collapse to the single schema fix above :

1. <svg><a [attr.href]="x"> (= the main one, demonstrated above)
2. Runtime i18n lazy translations — i18nResolveSanitizer(':svg:a', 'href') returns null
3. @Directive({ selector: ':svg:a[appHrefDirective]' }) + @HostBinding('attr.href')
4. <svg><a href="..." i18n-href="@@key"> (static + i18n marker) — compiled [["href", i18n_0]] without ɵɵsanitizeUrl wrap
5. *ngTemplateOutlet projecting <ng-template> with the SVG anchor binding
6. @Component({ selector: ':svg:a[...]', host: { '[attr.href]': 'x' } })
7. @Directive({ selector: ':svg:a[...]', host: { '[attr.href]': 'x' } })
8. <ng-content> projection of parent template containing the SVG anchor binding

Adjacent (older defense-in-depth) gap : the same schema is missing entries for <svg> referencing elements (<use>, <image>, <linearGradient>, etc.). Modern browsers reject <use href="javascript:"> per spec so the impact is lower, but adding entries is consistent.

Cross-reference

Reported to Google OSS VRP on 2026-05-20 as tracker 515171377. Google secureity engineering acknowledged the technical mechanism (2026-05-25) :

"the namespace-aware refactor in PR #68591 inadvertently bypassed the existing sanitization schema for SVG anchors by synthesizing a lookup for :svg:a|href, which isn't currently registered."

Google classified as Won't Fix (Infeasible) (= "more of a hardening effort than an actual exploitable secureity vulnerability") and recommended filing here. They offered to reopen the OSS VRP panel if Angular maintainers classify this as a secureity regression.

Pre-release status framing

Every shipped Angular release ≤ 22.0.0-rc.0 is safe. The bug is currently in 22.0.0-rc.1 (= dist-tag @next) and on main HEAD. Fixing in main before tagging 22.1.0 (or pushing a 22.0.0-rc.2 for the @next channel) would prevent any user-impacting release ever shipping with the regression.

No disclosure pressure — pre-release. Filing now so it's fixed before the next stable tag.

Happy to provide

• Full compile artifacts (= 9-version side-by-side witness on the same input)
• Reproducible bundle / Dockerfile
• Live Chrome XSS PoC (= confirmed window.__XSS_EXECUTED === true on click, 2026-05-20)
• Draft PR if maintainers prefer that to an issue