CVE-2026-72761
Webhook SSRF guard bypassed by IPv6 transition addresses (NAT64/6to4/Teredo pass is_global check) in vulnerability-lookup
- State
- Published
- Severity
- 6.9 Medium
- Published
- Aug 10, 2026
- Updated
- Aug 10, 2026
- Reserved
- Aug 10, 2026
Description
The webhook URL validator in `website/notifications/webhooks.py` uses `ip.is_global` to reject non-public addresses after DNS resolution. IPv6 transition addresses (NAT64 `64:ff9b::/96`, 6to4 `2002::/16`, Teredo `2001:0000::/32`) are classified as globally routable by IANA, so `is_global` returns `True` even when the embedded IPv4 targets a private, loopback, or cloud metadata destination. An attacker can register a webhook pointing at a hostname that resolves to a transition address to bypass the SSRF guard and exfiltrate vulnerability data to an internal endpoint.
The vulnerability was introduced on a non-release version. The fix was already done on HEAD. It only affects
organisation running the HEAD.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.9 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N | CIRCL |
Weaknesses
- CWE-918 Server-Side Request Forgery (SSRF)
Affected Products
| Product | Versions |
|---|---|
vulnerability-lookupvulnerability-lookup |
|
References
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