CVE-2026-39827Network attack vector

Authenticated server crash via unreleased rejected channels

Published May 22, 2026 · Updated May 22, 2026

Resource exhaustion in golang.org/x/crypto/ssh before 0.52.0 allows remote authenticated users to crash SSH servers via rejected channels. The channel.Reject path leaves rejected channels in the connection's internal state, so repeated openings retain memory instead of allowing garbage collection. An authenticated SSH client can exhaust server memory and terminate the process, interrupting every connection handled by that server.

CVSS severity6.5
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in golang.org/x/crypto/ssh before 0.52.0 allows remote authenticated users to crash SSH servers via rejected channels. The channel.Reject path leaves rejected channels in the connection's internal state, so repeated openings retain memory instead of allowing garbage collection. An authenticated SSH client can exhaust server memory and terminate the process, interrupting every connection handled by that server.

The record

CVE
CVE-2026-39827
Published
May 22, 2026
Updated
May 22, 2026
Vendor
golang.org/x/crypto
Product
golang.org/x/crypto/ssh
Classifications
CWE-924, T1499.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.52.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

golang.org/x/crypto · golang.org/x/crypto/sshversion=0 <0.52.0

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-924Improper Enforcement of Message Integrity During Transmission in a Communication Channel
T1499.002Service Exhaustion

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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