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CVE-2026-39832

⛔ critical
🔍 Scan for this CVE
Summary

When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not serialized in the request. Destination restrictions were silently stripped when forwarding keys, allowing unrestricted use of the key on the remote host. The client now serializes all constraint extensions. Additionally, the in-memory keyring returned by NewKeyring() now rejects keys with unsupported constraint extensions instead of silently ignoring them.

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 329,456 vulnerabilities in our database.

#40,532
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
Total
Complete system compromise possible
🏆 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:H/I:H/A:N
CWE IDs (Weakness Types)

📦 Affected Products 1

🔗 References 4

🔗 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-2026-39833 ⛔ critical 9.1 0.0 The in-memory keyring returned by NewKeyring() silently accepted keys with the ConfirmBeforeUse constraint but never enf... 2026-05-22
These CVEs affect the same products