CVE-2026-100187 PUBLISHED

AIL Framework Onion Module: Non-Onion URL Accepted as Crawler Task Due to Bypassed Domain Validation

Assigner: CIRCL
Reserved: 25.09.2026 Published: 25.09.2026 Updated: 25.09.2026

The Onion module in AIL Framework contained a performance shortcut in its URL extraction logic that accepted URLs as valid .onion targets based solely on a length check (exactly 69 characters) and a suffix check (ending in ".onion"), without performing proper hostname parsing or onion-domain validation. An unauthenticated attacker who could publish or control web content crawled by the framework could embed a crafted URL containing an IP address or non-onion hostname with a path ending in ".onion" that satisfied the length and suffix conditions. Such a URL would be extracted, its domain naively sliced from the string, and queued as a legitimate onion crawler task. This allowed unauthenticated content publishers to inject arbitrary non-onion targets into the crawler's task queue, influencing crawler behavior and potentially directing it toward unintended network resources. The vulnerability required no authentication, no user interaction, and only the ability to place crafted content in a location the framework would crawl. The security impact is a loss of integrity in the crawler's target selection: the framework processes and acts upon URLs that do not correspond to legitimate .onion services.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS Score: 6.9

Product Status

Vendor ail project
Product ail framework
Versions
  • affected from unspecified to 7.1 (excl.)

Solutions

The length-based shortcut that bypassed onion-domain validation is removed. Every extracted URL is now parsed using the standard URL domain extraction function, and the resulting hostname is validated against the existing onion-domain validation routine before the URL is added to the crawler task set. This ensures that only URLs whose hostname is a genuine .onion domain can be queued as crawler tasks.

Credits

  • Aurelien Thirion remediation developer
  • Jeroen Pinoy finder

References

Problem Types

  • CWE-20 Improper Input Validation CWE

Impacts

  • CAPEC-126 Parameter Tampering