CVE-2025-59837Public exploitNetwork attack vector

Unauthenticated SSRF via backslash URL normalization bypass

Published Oct 28, 2025 · Updated Oct 28, 2025

SSRF in Astro 5.13.4 through 5.13.9 allows remote attackers to make the image proxy fetch arbitrary URLs via crafted href values. The isRemotePath check treats backslash-prefixed and encoded-backslash URLs as local paths, so the /_image endpoint performs a server-side fetch after runtime normalization. No authentication or user interaction is required; SSRF is direct, while XSS depends on returned content being rendered by a browser.

CVSS severity7.2
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in Astro 5.13.4 through 5.13.9 allows remote attackers to make the image proxy fetch arbitrary URLs via crafted href values. The isRemotePath check treats backslash-prefixed and encoded-backslash URLs as local paths, so the /_image endpoint performs a server-side fetch after runtime normalization. No authentication or user interaction is required; SSRF is direct, while XSS depends on returned content being rendered by a browser.

The record

CVE
CVE-2025-59837
Published
Oct 28, 2025
Updated
Oct 28, 2025
Vendor
Astro Technology Company
Product
Astro
Classifications
CWE-918, CWE-79, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 28, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 2025Record 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.

  1. Affected versionversion=>= 5.13.4, < 5.13.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Astro Technology Company · Astroversion=>= 5.13.4, < 5.13.10

Published CVSS scores

7.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1190Exploit Public-Facing Application

Public exploit references

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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