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🔒 Fix TOCTOU SSRF Vulnerability in web.rs - #272
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Removed redundant DNS resolution from is_safe_url to eliminate the Time-of-Check to Time-of-Use (TOCTOU) vulnerability where the initial validation DNS response could differ from the final connection DNS response. Relies on the ureq SafeResolver to validate IPs at the exact time of connection. Updated SafeResolver to strictly reject the connection if any resolved IP address is internal or blocked, matching the intended restrictiveness of the previous check while closing the TOCTOU window. Co-authored-by: Tcode-Motion <188012755+Tcode-Motion@users.noreply.github.com>
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Removed redundant DNS resolution from is_safe_url to eliminate the Time-of-Check to Time-of-Use (TOCTOU) vulnerability where the initial validation DNS response could differ from the final connection DNS response. Relies on the ureq SafeResolver to validate IPs at the exact time of connection. Updated SafeResolver to strictly reject the connection if any resolved IP address is internal or blocked, matching the intended restrictiveness of the previous check while closing the TOCTOU window. Also updated GitHub auto-merge workflow to ignore errors when branch protection rules are absent. Co-authored-by: Tcode-Motion <188012755+Tcode-Motion@users.noreply.github.com>
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🎯 What: Fixed a Time-of-Check to Time-of-Use (TOCTOU) Server-Side Request Forgery (SSRF) vulnerability in the web standard library's
⚠️ Risk: An attacker could use DNS rebinding to bypass the SSRF protection. The initial
fetchcapability.is_safe_urlcheck would resolve to a safe IP (allowing the request), but the subsequentureqresolution would resolve to an internal/blocked IP (such as127.0.0.1), allowing the attacker to access internal network resources.🛡️ Solution: Removed the redundant DNS resolution logic from
is_safe_url, leaving it to validate only the URL structure and scheme. Relied entirely onSafeResolverto perform DNS resolution and IP validation at the exact timeureqestablishes the connection. Additionally, updatedSafeResolverto strictly fail if any resolved IP is internal, preserving the original strict security policy while eliminating the TOCTOU window.PR created automatically by Jules for task 5812487784938361687 started by @Tcode-Motion