Is CVE-2026-126362 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-126362 being exploited in the wild.

How severe is CVE-2026-126362?

Medium severity, with a CVSS score of 4, published 13 November 2026.

Which products and versions are affected?

Astro @Astrojs/Svelte 5.7.3 through 9.1.1; @astrojs/svelte (npm) >= 5.7.3, <= 9.1.1, SEMVER:introduced=5.7.3,fixed=9.1.2.

Is there a fix for CVE-2026-126362?

Yes. @astrojs/svelte (npm): upgrade to 9.1.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-126362 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-126362?

Check whether you run Astro @Astrojs/Svelte or @astrojs/svelte (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-126362: Astro @astrojs/svelte renderer HTML injection via unescaped slot names

Q: Is there a fix for CVE-2026-126362?

Yes. @astrojs/svelte (npm): upgrade to 9.1.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-126362 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-126362?

Check whether you run Astro @Astrojs/Svelte or @astrojs/svelte (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-126362 · Severity: medium · CVSS 4 · Published 2026-11-13

Astro is a web framework that builds content-driven websites, including blog platforms and documentation sites. A flaw in the Svelte component renderer could allow attackers to inject malicious HTML code through crafted slot names, potentially compromising web pages viewed by users. Exploitation requires a hydrated Svelte component with dynamic slot rendering controlled by an attacker.

Vendors: Astro, npm.

Quick answers

Is CVE-2026-126362 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-126362 being exploited in the wild.
How severe is CVE-2026-126362?: Medium severity, with a CVSS score of 4, published 13 November 2026.
Which products and versions are affected?: Astro @Astrojs/Svelte 5.7.3 through 9.1.1; @astrojs/svelte (npm) >= 5.7.3, <= 9.1.1, SEMVER:introduced=5.7.3,fixed=9.1.2.
Is there a fix for CVE-2026-126362?: Yes. @astrojs/svelte (npm): upgrade to 9.1.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-126362 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-126362?: Check whether you run Astro @Astrojs/Svelte or @astrojs/svelte (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

@astrojs/svelte (npm): upgrade to 9.1.2 or later
```
npm install @astrojs/svelte@9.1.2
```

Technical details

The @astrojs/svelte renderer failed to HTML-escape slot names when inserting them into the name attribute of astro-slot wrapper elements, allowing attribute termination and active HTML injection. Attack requires a hydrated Svelte component using a client:* directive with dynamic slot name rendering; components that did not render the attacker-chosen slot only emitted Astro's escaped fallback content. Both server-side and client-side hydration paths were vulnerable.

Affected products

Astro @astrojs/svelte 5.7.3 through 9.1.1

Identifiers

CVE-2026-126362
GHSA-f4j9-crrj-867q

Timeline

2026-11-13: disclosed
2026-10-28: patched: Fix released as version 9.1.2

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.