Cross-site scripting via cross-component ciphertext replay
Published May 13, 2026 · Updated May 13, 2026
Cross-site scripting in Astro before 6.1.10 allows remote attackers to inject script through replayed server-island ciphertext. The server-island endpoint decrypts props and slots under the same AES-GCM key without binding ciphertext to its component or parameter type, allowing a props value to be accepted as raw slot HTML. Exploitation requires server islands, dynamically rendered attacker-controlled props, matching prop and slot keys across two components, and a user who loads the affected page.
Summary
What happened
Cross-site scripting in Astro before 6.1.10 allows remote attackers to inject script through replayed server-island ciphertext. The server-island endpoint decrypts props and slots under the same AES-GCM key without binding ciphertext to its component or parameter type, allowing a props value to be accepted as raw slot HTML. Exploitation requires server islands, dynamically rendered attacker-controlled props, matching prop and slot keys across two components, and a user who loads the affected page.
The record
- CVE
- CVE-2026-45028
- Published
- May 13, 2026
- Updated
- May 13, 2026
- Vendor
- Astro Technology Company
- Product
- Astro
- Classifications
- CWE-79, CWE-323, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 13, 2026CVE publishedPublication date reported by the CVE source.
- May 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 6.1.10
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- ACSC2026-web-astronomical vulnerability exampleproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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