SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
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| benoitc | hackney | unaffected |
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| benoitc | hackney | unaffected |
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| Vendor | Product | Versions | ||||||||
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| Benoitc | Hackney |
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| Benoitc | Hackney |
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Vendor Workaround
Run the allowlist on the host that hackney_url:normalize/1 returns for the parsed URL, and strip a surrounding bracket pair and a trailing dot from it before the IP check, so the check sees the same address the connect path uses.
No CVSS v3.1
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.138% probability within 30 days)
| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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| Type | Values Removed | Values Added |
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| Description | Interpretation Conflict vulnerability in hackney_url in benoitc hackney allows Server Side Request Forgery via a percent-encoded bracketed IPv6 literal or an IP literal with a trailing dot. A host such as %5B%3A%3Affff%3A127%2E0%2E0%2E1%5D (decoding to [::ffff:127.0.0.1]) or 127.0.0.1. is not an IP address to a caller's allowlist built on uri_string:parse/1 and inet:parse_address/1, while hackney connects to the address it denotes. The same applies to a Location target when redirects are followed. The IP-literal gate that hackney_url:normalize/2 applies to a percent-decoded host, added to close the percent-encoded IP bypass of CVE-2026-47076, passes the decoded value to inet_parse:address/1 as is. The connect path in hackney_happy:parse_address/1 drops a surrounding bracket pair, and the resolver ignores a trailing dot, so both forms pass the gate and still reach the literal address. Domain names with a trailing dot and unencoded IPv6 literals are not affected. This issue affects hackney: from 4.0.1 before 4.9.0. | |
| Title | SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney | |
| First Time appeared |
Benoitc
Benoitc hackney |
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| Weaknesses | CWE-436 CWE-918 |
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| CPEs | cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Benoitc
Benoitc hackney |
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| References |
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| Metrics |
cvssV4_0
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