Large RSA Keys in Go crypto/tls Causing CPU Exhaustion
CVE-2023-29409 Published on August 2, 2023
Large RSA keys can cause high CPU usage in crypto/tls
Extremely large RSA keys in certificate chains can cause a client/server to expend significant CPU time verifying signatures. With fix, the size of RSA keys transmitted during handshakes is restricted to <= 8192 bits. Based on a survey of publicly trusted RSA keys, there are currently only three certificates in circulation with keys larger than this, and all three appear to be test certificates that are not actively deployed. It is possible there are larger keys in use in private PKIs, but we target the web PKI, so causing breakage here in the interests of increasing the default safety of users of crypto/tls seems reasonable.
Products Associated with CVE-2023-29409
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Affected Versions
Go standard library crypto/tls:- Before 1.19.12 is affected.
- Version 1.20.0-0 and below 1.20.7 is affected.
- Version 1.21.0-0 and below 1.21.0-rc.4 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.