CVE intelligence

CVE-2023-29409

Vulnerability intelligence

Published Aug 2, 2023Sources checked Oct 30, 2026

5.3MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2023-29409 and is rated Medium severity with a CVSS score of 5.3. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Sep 17, 2026

CBL-Mariner Releases

Vendor-listed releases

1.21.6-1
1.20.7-1

CISA KEVNot listedBased on the latest collected catalog

EPSS1.6%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2023-29409?

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.

Source: NVD