CVE-2026-33753: Improper Certificate Validation in rfc3161-client
trailofbits · rfc3161-client
Affected: trailofbits rfc3161-client · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 9% of scored CVEs
DescriptionCVE.org
rfc3161-client is a Python library implementing the Time-Stamp Protocol (TSP) described in RFC 3161. Prior to 1.0.6, an Authorization Bypass vulnerability in rfc3161-client's signature verification allows any attacker to impersonate a trusted TimeStamping Authority (TSA). By exploiting a logic flaw in how the library extracts the leaf certificate from an unordered PKCS#7 bag of certificates, an attacker can append a spoofed certificate matching the target common_name and Extended Key Usage (EKU) requirements. This tricks the library into verifying these authorization rules against the forged certificate while validating the cryptographic signature against an actual trusted TSA (such as FreeTSA), thereby bypassing the intended TSA authorization pinning entirely. This vulnerability is fixed in 1.0.6.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- trailofbits · rfc3161-client< 1.0.6
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- trailofbits
- Published
- April 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-33753 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.