CVE-2026-72761

Webhook SSRF guard bypassed by IPv6 transition addresses (NAT64/6to4/Teredo pass is_global check) in vulnerability-lookup

Published Aug 10, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Circl
Circl vulnerability-lookup
Vendors & Products Circl
Circl vulnerability-lookup
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Webhook SSRF guard bypassed by IPv6 transition addresses (NAT64/6to4/Teredo pass is_global check) in vulnerability-lookup
Weaknesses CWE-918
References
Metrics cvssV4_0

{'score': 6.9, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
CIRCL
Published
Updated
Aug 10, 2026, 5:00 PM
Reserved
Aug 10, 2026, 2:32 PM
Status
Deferred
Published
Aug 10, 2026, 3:17 PM
Modified
Aug 26, 2026, 4:49 PM