CVE-2026-39827: Golang.org/x/crypto Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-qpw4-5x99-6vjp
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CVSS 6.5
CWE-924
Published
Advisory Summary

CVE-2026-39827 is a MODERATE (CVSS 6.5) denial of service vulnerability (CWE-924: Improper Enforcement of Message Integrity During Transmission in a Communication Channel) affecting Golang.org/x/crypto libraries in the Go ecosystem. The issue involves invoking memory leak when rejecting channels can lead to dos. Remediation is available by upgrading affected packages to version 0.52.0.

CVE-2026-39827 at a Glance

CVE Identifier CVE-2026-39827
GHSA Identifier GHSA-qpw4-5x99-6vjp
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-924: Improper Enforcement of Message Integrity During Transmission in a Communication Channel
Affected Product Golang.org/x/crypto
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-39827

To remediate this vulnerability, upgrade all affected Golang.org/x/crypto dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

golang.org/x/crypto fixed: 0.52.0 
Upgrade golang.org/x/crypto to 0.52.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for golang.org/x/crypto

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-39827, inspect your project dependencies for Golang.org/x/crypto:

inspect dependencies for golang.org/x/crypto

Analyze the terminal output to locate any version of Golang.org/x/crypto in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.52.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-924: Improper Enforcement of Message Integrity During Transmission in a Communication Channel, where the product establishes a communication channel with an endpoint and receives a message from that endpoint, but it does not sufficiently ensure that the message was not modified during transmission. In Golang.org/x/crypto, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly removed from the connection's internal state and released for garbage collection.

CVE-2026-39827 Affected Golang.org/x/crypto Versions

1 component(s)
Fixed Versions:
0.52.0
Product / Package Ecosystem Affected Versions Fixed Version
golang.org/x/crypto
golang/golang.org/x/crypto
Go
< 0.52.0
0.52.0

References

NVD — CVE-2026-39827 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39827
cs.opensource.google/go/x/crypto PACKAGE
https://cs.opensource.google/go/x/crypto
go.dev/cl/781320 WEB
https://go.dev/cl/781320
go.dev/issue/35127 WEB
https://go.dev/issue/35127
groups.google.com/g/golang-announce/c... WEB
https://groups.google.com/g/golang-announce/c/a082jnz-LvI
pkg.go.dev/vuln/go-2026-5016 WEB
https://pkg.go.dev/vuln/GO-2026-5016

Frequently Asked Questions

What is CVE-2026-39827?
CVE-2026-39827 is a security vulnerability in Golang.org/x/crypto involving Invoking memory leak when rejecting channels can lead to DoS under CWE-924: Improper Enforcement of Message Integrity During Transmission in a Communication Channel.
Which Golang.org/x/crypto versions are affected?
Affected versions include releases prior to 0.52.0 across affected packages: golang.org/x/crypto.
What version fixes CVE-2026-39827?
Upgrading to 0.52.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is golang.org/x/crypto affected?
Yes, golang.org/x/crypto is affected in releases prior to 0.52.0. Upgrade your dependency to 0.52.0 or later.
What is the CVSS score of CVE-2026-39827?
CVE-2026-39827 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-39827?
CVE-2026-39827 is classified under CWE-924: Improper Enforcement of Message Integrity During Transmission in a Communication Channel (The product establishes a communication channel with an endpoint and receives a message from that endpoint, but it does not sufficiently ensure that the message was not modified during transmission.).
How can I check Go dependencies for CVE-2026-39827?
Run the dependency tree command: 'inspect dependencies for golang.org/x/crypto'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qpw4-5x99-6vjp",
  "modified" : "2026-07-07T15:24:35Z",
  "published" : "2026-06-25T22:15:43Z",
  "aliases" : [ "CVE-2026-39827" ],
  "summary" : "golang.org/x/crypto: Invoking memory leak when rejecting channels can lead to DoS",
  "details" : "An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly removed from the connection's internal state and released for garbage collection.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "golang.org/x/crypto"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.52.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39827"
  }, {
    "type" : "PACKAGE",
    "url" : "https://cs.opensource.google/go/x/crypto"
  }, {
    "type" : "WEB",
    "url" : "https://go.dev/cl/781320"
  }, {
    "type" : "WEB",
    "url" : "https://go.dev/issue/35127"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/golang-announce/c/a082jnz-LvI"
  }, {
    "type" : "WEB",
    "url" : "https://pkg.go.dev/vuln/GO-2026-5016"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-924" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-25T22:15:43Z",
    "nvd_published_at" : "2026-05-22T04:16:21Z"
  }
}