CVE-2026-39830
Published: May 22, 2026· Updated: May 22, 2026
Official Description
A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection's read loop. The blocked goroutine could not be released by calling Close(), resulting in a resource leak per connection. Unsolicited global responses are now discarded.
Risk Analysis
This critical vulnerability (CVSS 9.1) in OpenSSH can lead to a denial of service. A malicious SSH peer can send unsolicited global request responses, filling an internal buffer and blocking the connection's read loop. This results in a resource leak, potentially impacting system availability.
No public exploit is currently known for this remotely exploitable vulnerability. The low attack complexity suggests that an attacker could easily trigger this condition.
Update OpenSSH to a version that discards unsolicited global responses. Implement network monitoring to detect and block unusual SSH traffic patterns that might indicate an attempt to exploit this vulnerability.
Technical Analysis
CVE-2026-39830 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), availability disruption (denial of service), with a CVSS base score of 9.1.
CVSS v3.1 Vector Breakdown
Exploit & PoC Resources
All References (5)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-39830 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts