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🛡️ CVE-2026-45028 — astro

🟢 CVSS 2.0 — Low ✅ No Known Exploit CWE-323 OSV
2.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Astro: Server island encrypted parameters vulnerable to cross-component replay

Impact

Astro versions prior to 6.1.10 used AES-GCM encryption to protect the confidentiality and integrity of server island props and slots parameters, but did not bind the ciphertext to its intended component or parameter type. An attacker could replay one component's encrypted props (p) value as another component's slots (s) value, or vice versa.

Since slots contain raw unescaped HTML while props may contain user-controlled values, this could lead to XSS in applications that meet all of the following conditions:

  • The application uses server islands
  • Two different server island components share the same key name for a prop and a slot
  • An attacker has full control over the value of the overlapping prop (requires a dynamically rendered page)

These conditions are very unlikely to occur in real-world production applications.

Patches

This has been patched in [email protected].

The fix binds each encrypted parameter to its target component and purpose using AES-GCM authenticated additional data (AAD). Each ciphertext now includes context like props:IslandName or slots:IslandName, so encrypted data for one component cannot be replayed against a different component, and encrypted props cannot be reused as slots.

References

  • Fix PR: https://github.com/withastro/astro/pull/16457
  • Example demonstrating the vulnerability: https://github.com/CyberSecurityAustria/ACSC2026-web-astronomical

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality none, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Attack requirements: Present — the target has to be in a particular state for the attack to work.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Confidentiality impact: None.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-45028 is classified as CWE-323: Reusing a Nonce, Key Pair in Encryption. Nonces should be used for the present occasion and only once.

Affected software

CVE-2026-45028 is recorded against 1 package.

  • astro

Timeline and source

Published on 13 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)

Other advisories for this package

astro has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-323: Reusing a Nonce, Key Pair in Encryption) in other software:

Details

Severity LOW
CVSS Score 2.0
CVSS Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
CWE CWE-323
Public Exploit ✅ No
Source OSV
Published 2026-05-13
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
astro — —

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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