CVE-2023-29409

Large RSA keys can cause high CPU usage in crypto/tls

MEDIUM
5.3
CVSS Score
Published: August 2, 2023 at 07:47 PM UTC
Updated: June 17, 2026 at 05:49 AM UTC
2 products affected across 2 vendorsGoGo

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Severity
MEDIUM5.3
Exploit prediction
EPSS 2%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.19.121.20.0 ≤ v < 1.20.71.21.0 rc11.21.0 rc21.21.0 rc3
Affected range stops below 1.19.12, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.20.7, so it looks safe — our inference, not a vendor statement
v < 1.19.121.20.0-0 ≤ v < 1.20.71.21.0-0 ≤ v < 1.21.0-rc.41.20.0-01.21.0-0
Affected range stops below 1.19.12, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.20.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.21.0-rc.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-400

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