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Let's Encrypt: 2019.08.20 Incident: Incorrect OCSP responses under certain conditions

RESOLVED FIXED Internet Security Research Group

AI Summary

On August 20, 2019, Let's Encrypt received a report regarding incorrect OCSP responses due to a bug in their CDN provider, Akamai. The issue arose when OCSP requests were made with a specific header, leading to valid but incorrect responses. After identifying the problem, Let's Encrypt worked with Akamai to implement a temporary workaround and subsequently confirmed a permanent fix. The incident did not affect the integrity of certificate issuance, and no problematic certificates were issued.

Model: gpt-4o-mini Generated: 2026-06-13 20:00 UTC Confidence: 0.90

Chronology

2019-08-20 Initial report received from community member
2019-08-20 Ticket filed with Akamai
2019-08-21 Temporary workaround applied
2019-08-21 Private disclosures made to root programs
2019-08-26 Akamai confirms global permanent fix

Participants

Josh Aas Stefan Eissing W. Thayer

External References

Original Bugzilla Case community.letsencrypt.org

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