Cross-site scripting via spread attributes in Svelte SSR (CVE-2026-27121) | HOL Guard CVE

Medium severityCVE-2026-27121GHSA-F7GR-6P89-R883

Cross-site scripting via spread attributes in Svelte SSR

Answer in brief

CVE-2026-27121 records a Medium severity vulnerability in Cross-site scripting via spread attributes in Svelte SSR. The current sources do not mark it as known exploited. The current feed maps svelte (npm). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Feb 18, 2026Updated Feb 18, 2026Source checked Aug 26, 2026First seen by HOL Aug 25, 2026Material review Feb 18, 2026

Upstream Advisory

Key facts

Risk: Medium
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps svelte (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
sveltenpm	<=5.51.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for svelte.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Feb 18, 2026
Evidence: source:ghsa:source_dates:source-dates:record
Source modified
Feb 18, 2026
Evidence: source:ghsa:source_dates:source-dates:record
First seen by HOL
Aug 25, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source description

Versions of svelte prior to 5.51.5 are vulnerable to cross-site scripting (XSS) during server-side rendering. When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers.

Quoted source text, attributed separately from HOL analysis.