BentoPDF: Workflow Import Allows Unvalidated TSA URL Leading to PDF Hash Exfiltration via RFC 3161 Requests

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

BentoPDF is a client-side PDF toolkit that is self hostable. In 2.8.6 and earlier, deserializeWorkflow() accepts the Timestamp node's tsaUrl control from imported JSON without schema or destination validation. When a user imports the crafted workflow and runs it against a PDF, timestampPdf() sends an RFC 3161 TimeStampReq containing the PDF's SHA-256 MessageImprint to the attacker-selected endpoint. The default self-hosted configuration does not set VITE_CORS_PROXY_URL, so the request bypasses the proxy's ALLOWED_TSA_HOSTS checks and is sent directly. The disclosed digest can confirm that a document matches a known file and can correlate the same document across users without revealing its contents. This vulnerability is fixed in 2.8.7.

Source published

24 Sep 2026 15:33:44 UTC

Source modified

29 Sep 2026 02:49:15 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 3.1 · 3.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N