# CVE-2026-45028: Astro cross-component replay in server islands

Source: https://junglewise.ai/threats/cve-2026-45028-astro-server-island-cross-component-replay-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-13. Updated: 2026-05-14  
License: CC BY 4.0 with a link back

CVE-2026-45028 · Severity: medium · CVSS 6.1 · Published 2026-05-13

Astro is a popular web framework used to build fast, content-focused websites. A vulnerability in its "server islands" feature could allow an attacker to manipulate how data is displayed on a page, potentially leading to malicious scripts being executed in a user's browser. While this could lead to unauthorized actions or data theft, the specific conditions required for a successful attack are rare in typical production environments.

Technologies: [astro (npm)](https://junglewise.ai/threats/technologies/astro). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-45028 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-45028 being exploited in the wild.

**How severe is CVE-2026-45028?** Medium severity, with a CVSS score of 6.1, published 13 May 2026.

**Which products and versions are affected?** astro (npm) < 6.1.10, SEMVER:introduced=0,fixed=6.1.10.

**Is there a fix for CVE-2026-45028?** Yes. astro (npm): upgrade to 6.1.10 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-45028 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-45028?** Check whether you run astro (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

- astro (npm): upgrade to 6.1.10 or later

  ```sh
  npm install astro@6.1.10
  ```


## Technical details

Astro versions prior to 6.1.10 used AES-GCM to encrypt server island parameters (props and slots) but failed to bind the ciphertext to a specific component or parameter type. This lack of cryptographic binding allows an attacker to perform a replay attack, taking an encrypted 'props' value (which may contain user-controlled data) and submitting it as a 'slots' value. Because slots are rendered as raw, unescaped HTML, this can result in Cross-Site Scripting (XSS) if a prop and slot share the same key name across different components. The fix introduces Authenticated Additional Data (AAD) to the AES-GCM process, binding the ciphertext to the specific component name and parameter type.

## Affected products

- withastro astro < 6.1.10

## Identifiers

- CVE-2026-45028
- GHSA-xr5h-phrj-8vxv

## Timeline

- 2026-05-07: patched: Fix published in version 6.1.10
- 2026-05-13: disclosed: GitHub Advisory published

## References

- [https://api.github.com/users/Popax21](https://api.github.com/users/Popax21)
- [https://github.com/Popax21](https://github.com/Popax21)
- [https://api.github.com/users/Popax21/gists%7B/gist_id%7D](https://api.github.com/users/Popax21/gists%7B/gist_id%7D)
- [https://api.github.com/users/Popax21/repos](https://api.github.com/users/Popax21/repos)
- [https://avatars.githubusercontent.com/u/29798799?v=4](https://avatars.githubusercontent.com/u/29798799?v=4)
- [https://api.github.com/users/Popax21/events%7B/privacy%7D](https://api.github.com/users/Popax21/events%7B/privacy%7D)

## Related threats

- [Astro HTML injection in script and style element rendering](https://junglewise.ai/threats/cve-2026-114128-astro-is-a-web-framework-for-content-driven-websites-prior-to-7)
- [Astro CSS injection in View Transition animation values](https://junglewise.ai/threats/cve-2026-114127-astro-is-a-web-framework-for-content-driven-websites-from-7-1-0)
- [Astro remote code execution via AVIF image processing](https://junglewise.ai/threats/astro-remote-code-execution-via-avif-image-processing-6b99ffe8)
- [Astro authorization bypass in base path stripping](https://junglewise.ai/threats/cve-2026-84376-astro-authorization-bypass-in-base-path-stripping)
- [Astro composable astro/hono pipeline CSRF via origin check bypass](https://junglewise.ai/threats/cve-2026-73423-astro-composable-astro-hono-pipeline-csrf-via-origin-check-bypass)