Let’s Encrypt will be reducing the validity period of the certificates we issue. We currently issue certificates valid for 90 days, which will be cut in half to 45 days by 2028.
This change is being made along with the rest of the industry, as required by the CA/Browser Forum Baseline Requirements, which set the technical requirements that we must follow. All publicly-trusted Certificate Authorities like Let’s Encrypt will be making similar changes. Reducing how long certificates are valid for helps improve the security of the internet, by limiting the scope of compromise, and making certificate revocation technologies more efficient.



Isn’t this just CRL in reverse? And CRL sucks or we wouldn’t be having this discussion. Part of the point of cryptographically signing a cert is so you don’t have to do this if you trust the issuer.
Cryptography already makes it infeasible for a malicious actor to create a fake cert. The much more common attack vector is having a legitimate cert’s private key compromised.
No, these are completely separate issues.
This is just one example why we have certificate transparency. Revocation wouldn’t be useful if it isn’t even known which certificates need revocation.
Source
Or the more likely a rouge certificate authority giving out certs it shouldn’t.