SSRF allowlist bypass via percent-encoded host
Published May 25, 2026 · Updated May 25, 2026
SSRF in Benoit Chesneau hackney 0.13.0 through 4.0.0 allows remote attackers to reach internal services through crafted URLs. hackney_url:normalize/2 decodes a percent-encoded host after caller-side validation, converting a permitted non-IP token into the connection's IP address. Exploitation requires a consuming application to pass attacker-supplied URLs, after which loopback, private-network, or cloud metadata endpoints become reachable.
Summary
What happened
SSRF in Benoit Chesneau hackney 0.13.0 through 4.0.0 allows remote attackers to reach internal services through crafted URLs. hackney_url:normalize/2 decodes a percent-encoded host after caller-side validation, converting a permitted non-IP token into the connection's IP address. Exploitation requires a consuming application to pass attacker-supplied URLs, after which loopback, private-network, or cloud metadata endpoints become reachable.
The record
- CVE
- CVE-2026-47076
- Published
- May 25, 2026
- Updated
- May 25, 2026
- Vendor
- Benoit Chesneau
- Product
- Hackney
- Classifications
- CWE-436, CWE-918, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 25, 2026CVE publishedPublication date reported by the CVE source.
- May 25, 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=0.13.0 <4.0.1
- Affected versionversion=4d725507588942fd00efca15b86da3273656510a <452620a92ec1da2e6b4862a049a2a4f04b42068f
What conditions does exploitation require?
What is affected?
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
- Maintainer advisory percent-encoded host proof of conceptproof 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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