CVE-2026-39830 | Invoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/ssh

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.

Published: 2026-05-22 Last update: 2026-06-02 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-39830 is rated Moderate Risk (42.5/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.06%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-39830

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-28 0.02% 0.06% +0.04%
2 2026-05-22 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-39830

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.2 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-39830

OS Trackers for CVE-2026-39830

vendor priority summary link
debian not yet assigned CVE-2026-39830 not yet assigned priority: Debian including 1 source packages (golang-go.crypto), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-39830
suse high — https://www.suse.com/security/cve/CVE-2026-39830/
ubuntu medium CVE-2026-39830 medium priority: Ubuntu including 4 source packages (golang-go.crypto, google-guest-agent, lxd, snapd), 31 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): needs-triage 18, needed 7, DNE 4, not-affected 1, released 1. https://ubuntu.com/security/CVE-2026-39830

Affected software / configurations for CVE-2026-39830

Vendor Product Version Raw CPE
golang crypto < 0.52.0 cpe:2.3:a:golang:crypto:*:*:*:*:*:go:*:*

References for CVE-2026-39830

cvelogic Threat Intelligence