SSRF via unbound DNS validation
Published Sep 15, 2026 · Updated Sep 15, 2026
TOCTOU in Doyensec safeurl 0.1.0 onward allows remote attackers to reach blocked internal destinations through DNS rebinding. The validator approves one resolved address but passes the original hostname to the HTTP client, which resolves it again when connecting. An attacker must control the hostname's DNS answers; alternating a permitted address with a blocked address enables SSRF into internal services.
Summary
What happened
TOCTOU in Doyensec safeurl 0.1.0 onward allows remote attackers to reach blocked internal destinations through DNS rebinding. The validator approves one resolved address but passes the original hostname to the HTTP client, which resolves it again when connecting. An attacker must control the hostname's DNS answers; alternating a permitted address with a blocked address enables SSRF into internal services.
The record
- CVE
- CVE-2026-77972
- Published
- Sep 15, 2026
- Updated
- Sep 15, 2026
- Vendor
- Doyensec
- Product
- safeurl
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 15, 2026CVE publishedPublication date reported by the CVE source.
- Sep 15, 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=0.1.0 <*
- Affected versionversion=feabbd0a13f83028ab24b71710526e9da9841f70 <*
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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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
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Public exploit references
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Technologies
Your stack
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Your stack
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