Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh

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Summary

CVECVE-2026-39834
StatePUBLISHED
AssignerGo
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-22 04:16:24 UTC
Updated2026-05-28 15:03:47 UTC
DescriptionWhen writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS: 0.000420000 probability, percentile 0.128120000 (date 2026-05-27)

Problem Types: CWE-190 | CWE-190: Integer Overflow or Wraparound

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Golang Crypto All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Golang.orgxcrypto Golang.org/x/crypto/ssh affected 0.52.0 semver Not specified

References

ReferenceSourceLinkTags
groups.google.com/g/golang-announce/c/a082jnz-LvI [email protected] groups.google.com Mailing List
go.dev/issue/79567 [email protected] go.dev Issue Tracking
go.dev/cl/781663 [email protected] go.dev Issue Tracking
pkg.go.dev/vuln/GO-2026-5020 [email protected] pkg.go.dev Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: NCC Group Cryptography Services, sponsored by Teleport (en)

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