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CVE-2026-77866

SSRF protection bypass in safeurl via IPv6 addresses and unresolvable hosts PUBLISHED

Description (CNA)

Server-Side Request Forgery (SSRF) vulnerability in Slab safeurl allows an attacker who controls a validated URL to reach internal network destinations the library is configured to block. Only IPv4 addresses are matched against the reserved ranges and the blocklist. Every other address is treated as matching nothing, so a destination that is rejected in its IPv4 form is accepted when written as an IPv6 address, IPv6 entries in the blocklist never match, and a host that resolves to no IPv4 address is accepted regardless of where it points. Deployments that rely on the allowlist instead are unaffected, because there an unmatched address is rejected. This issue affects safeurl: from 0.1.0 onward.

Affected (CNA)

Vendor / productVersions
Slab / safeurlaffected 0.1.0 before *
Slab / safeurlaffected feabbd0a13f83028ab24b71710526e9da9841f70 before *

CWE

CWE-918, CWE-636

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.