23 Oct 2026 15:48:27 UTC
safeurl validated address is not bound to the request, allowing DNS rebinding
cve-program · CVE-2026-77972 · Published
CVE-2026-77972
safeurl validated address is not bound to the request, allowing DNS rebinding
CVSS 4.0 9.0 CRITICALCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-77972
PublishedTime-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname's DNS responses to reach internal network destinations that validation rejected. Validation returns a verdict and not the address it approved, so the HTTP clients the library ships receive the original hostname and resolve it a second time when the request is made. An attacker who controls the authoritative DNS for a name can answer the first lookup with a permitted address and the second with a blocked one, and the request then reaches a destination validation never approved. The same window opens without an attacker whenever a name legitimately resolves to different addresses across lookups, such as short record lifetimes or rotation between several addresses. This issue affects safeurl: from 0.1.0 onward.
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