← Internet Security Research Group cases
Bugzilla #1853719 Certificate Problem Report

Once Revoked Let's Encrypt Certificate Actively Signing Malware

RESOLVED INVALID Internet Security Research Group
AI Summary

A user reported that an old Let's Encrypt CA certificate is being used to sign malware. The claim suggests that this certificate, which was previously revoked, is being bundled with malicious software. However, the Mozilla team indicated that there is insufficient evidence of a private key compromise, as the public certificate can be misused without indicating a vulnerability in the CA itself. The case was ultimately resolved as invalid due to lack of substantiated claims regarding the misuse of the private key.

Model: gpt-4o-mini Generated: 2026-06-13 21:18 UTC Confidence: 0.50
Chronology
  1. User reported the misuse of a revoked Let's Encrypt certificate.
  2. Mozilla team indicated intent to close the case as invalid.
  3. Case officially closed as invalid.
Participants
lneubecker1972@gmail.com bwilson@mozilla.com
External References
Similar Local Cases
#1645276 RESOLVED Certificate Problem Report Opened 2020-06-12 · Closed 2023-02-22 · 57% similar
Let's Encrypt: Expired ISRG Root OCSP X1 Certificate
#1954861 RESOLVED Certificate Problem Report Opened 2025-03-18 · Closed 2025-04-09 · 56% similar
Let's Encrypt: Early CRL Removal Incident
#1639794 RESOLVED Certificate Problem Report Opened 2020-05-21 · Closed 2023-02-22 · 56% similar
Let's Encrypt: Failure to revoke key-compromised certificate within 24 hours
#1789521 RESOLVED Certificate Problem Report Opened 2022-09-06 · Closed 2024-05-09 · 55% similar
Let's Encrypt: Certificates issued to Elliptic Curve Debian Weak Keys
#1391867 RESOLVED Certificate Problem Report Opened 2017-08-19 · Closed 2023-02-22 · 49% similar
Let's Encrypt: Non-BR-Compliant Certificate Issuance
#1966515 RESOLVED Certificate Problem Report Opened 2025-05-14 · Closed 2025-06-04 · 48% similar
Let's Encrypt: Issuance for Invalid Internationalized Domain Name
#1625322 RESOLVED Certificate Problem Report Opened 2020-03-26 · Closed 2023-02-22 · 48% similar
Let's Encrypt: Failure to revoke key-compromised certificates within 24 hours
#1742704 RESOLVED Certificate Problem Report Opened 2021-11-23 · Closed 2024-05-09 · 48% similar
Let's Encrypt: Potential Denial of Service against websites with broad private key reuse

We use only essential cookies and local browser storage for preferences and security. See our Privacy Policy for details.

Confirm action