CVE-2026-39834

⛔ critical

Summary

When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

CVSS Score

9.1

Critical

EPSS Score

0.1

Exploit Probability

Published Date

2026-05-22

First Seen: 2026-05-23

📊 Relative Risk Intelligence

This CVE is High Risk - more severe than 87.7% of all 327,035 vulnerabilities in our database.

#40,172

Top 25% most severe

Severity Percentile

🎯 CISA SSVC Assessment Updated: May 22, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

YES

Can be exploited automatically

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

NCC Group Cryptography Services, sponsored by Teleport

SSVC data provided by CISA

Last Modified 2026-05-28

Source NVD 🔗

CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CWE IDs (Weakness Types)

CWE-190

📦 Affected Products 1

Vendor	Product	Status	Affected Versions
golang	crypto	Affected	< 0.52.0

🔗 References 4

https://go.dev/cl/781663

Issue Tracking

https://go.dev/issue/79567

Issue Tracking

https://groups.google.com/g/golang-announce/c/a082jn...

Mailing List

https://pkg.go.dev/vuln/GO-2026-5020

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-39827	🔶 medium	6.5	0.0	An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory gr...	2026-05-22
CVE-2026-39828	🔶 medium	6.3	0.0	When an SSH server authentication callback returned PartialSuccessError with non-nil Permissions, those permissions were...	2026-05-22
CVE-2026-39829	⚠️ high	7.5	0.0	The RSA and DSA public key parsers did not enforce size limits on key parameters. A crafted public key with an excessive...	2026-05-22
CVE-2026-39830	⛔ critical	9.1	0.1	A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection...	2026-05-22
CVE-2026-39831	⛔ critical	9.1	0.0	The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did...	2026-05-22
CVE-2026-39832	⛔ critical	9.1	0.1	When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not serializ...	2026-05-22

These CVEs affect the same products