CVE-2026-39830

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.

Overview

State: PUBLISHED
Assigner (CNA): Go
CVSS severity: critical
CVSS score: 9.1 / 10
CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Effective score: 9.1 / 10 CRITICAL source: CNA overview
MSRC score: 9.1 / 10 CRITICAL MS rating: Important
CWE(s): CWE-833: Deadlock
Reserved: 2026-04-07
Published: 2026-05-22 02:31 UTC
Last updated: 2026-05-22 18:54 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/39xxx/CVE-2026-39830.json
Linked Threat: CVE-2026-39830 — CVE-2026-39830

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-05-22 04:16:22 UTC
NVD last modified: 2026-05-22 04:16:22 UTC
EPSS score: 0.0004 (probability of exploitation in next 30 days)
EPSS percentile: 12.76% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-31397
Assigner: Go
Published: May 22, 2026, 2:31:27 AM
Updated: May 22, 2026, 6:54:54 PM
EUVD base score (CVSS 3.1): 9.1 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EUVD-reported EPSS: 0.0600
Vendors: golang.org/x/crypto
Products: golang.org/x/crypto/ssh (0 <0.52.0)

ENISA 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.

EUVD references (5)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-07-28 03:00 UTC (source: CVRF).

MS severity: Important
MS CVSS base score: 9.1 / 10 (temporal 8.3)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H/E:U
Release: 2026-May

Microsoft remediations / KB articles (2)

CBL-Mariner Releases — Vendor Fix / Security Update (fixed build 1.12.15-8)
https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade — None Available / CBL-Mariner Releases

Affected products (1)

Vendor	Product	Versions	Platforms
golang.org/x/crypto	golang.org/x/crypto/ssh	`0` (affected)	—

Vendor references (5)

References embedded in the original CVE record by the assigning CNA.

Web references (10)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

None Available msrc
MSRC update guide: CVE-2026-39830 msrc
https://www.first.org/epss/ tenable:www.first.org
https://groups.google.com/g/golang-announce/c/a082jnz-LvI tenable:groups.google.com
https://go.dev/issue/79564 tenable:go.dev
https://go.dev/cl/781664 tenable:go.dev
https://nvd.nist.gov/vuln/detail/CVE-2026-39830 tenable:nvd.nist.gov
https://pkg.go.dev/vuln/GO-2026-5017 tenable:pkg.go.dev
https://www.cve.org/CVERecord?id=CVE-2026-39830 tenable:www.cve.org
https://go.dev/cl/781640 tenable:go.dev

NVD-tagged references (5)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://go.dev/cl/781640 security@golang.org
https://go.dev/cl/781664 security@golang.org
https://go.dev/issue/79564 security@golang.org
https://groups.google.com/g/golang-announce/c/a082jnz-LvI security@golang.org
https://pkg.go.dev/vuln/GO-2026-5017 security@golang.org

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

Security Advisory Bulletin 064 | Ubiquiti Community

web:community.ui.com

Published: May 21, 2026 Updated: May 22, 2026 Version: 1.1 Revision: 1.1 Summary 1 of 5 A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS devices to execute a Command Injection. Affected Products: UniFi OS Server (Version 5.0.6 and earlier) Mitigation : Update your UniFi OS Server to Version 5.0.8 or later ...

2026-05-26 03:00 UTC
CISA Warns of Exploited Microsoft Defender 0-Day Flaws

web:cyberpress.org

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added two actively exploited Microsoft Defender vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, issuing an urgent remediation directive for federal agencies with a due date of June 3, 2026 .

2026-05-26 03:00 UTC
Security Update Guide - Microsoft

web:msrc.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-05-26 03:00 UTC
CVE-2026-39830 : Resource Leak Vulnerability in SSH Connections of Go ...

web:securityvulnerability.io

What is CVE-2026-39830 ? An attacker exploiting a vulnerability in the Go programming language could intentionally send unsolicited global request responses during SSH connections.

2026-05-26 03:00 UTC
Landing Page | ServiceNow Common Vulnerabilities & Exposures (CVE ...

web:support.servicenow.com

Overview The advisories below document publicly disclosed Common Vulnerabilities and Exposures ( CVEs ) in the Now Platform by ServiceNow. Because ServiceNow uses various methods to communicate vulnerability information, patches, and other fixes, customers should review family, security patch , and hotfix release notes, which are available at https://docs.servicenow.com, for a complete list of ...

2026-05-26 03:00 UTC
April 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft's April 2026 Patch Tuesday addresses 164 CVEs , featuring 8 Critical vulnerabilities, one exploited zero-day, and one disclosed zero-day.

2026-05-26 03:00 UTC
CVE: Common Vulnerabilities and Exposures

web:www.cve.org

At cve .org, we provide the authoritative reference method for publicly known information-security vulnerabilities and exposures

2026-05-26 03:00 UTC
PDF New England District Compensatory Mitigation Standard Operating Procedures

web:www.nae.usace.army.mil

This New England District's Regulatory Division Standard Operating Procedure (SOP) is for use when the Corps determines PRM is appropriate for a project and for third party mitigation projects ( mitigation banks and ILF programs). When a mitigation bank or an ILF program is available, compensatory mitigation conducted using these options is considered preferable to PRM alternatives according ...

2026-05-26 03:00 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-05-26 03:00 UTC
Patch Tuesday May 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-05-26 03:00 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-39830.json.

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              "baseSeverity": "CRITICAL",
              "confidentialityImpact": "HIGH",
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        {
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      "title": "Invoking  client can cause server deadlock on unexpected responses in golang.org/x/crypto/ssh"
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