High Denial of service

CVE-2026-78662 — Prevent DoS on deadlocked undecided channel in golang.org/x/crypto/ssh

Previously, a channel registered in the mux's chanList is not usable until it is established. A malicious peer was able flood the channel's incomingRequests, deadlocking the entire connection. Now, we add an atomic established state, set when a channel becomes usable. Until such a time, handlePacket drops every packet other than the open confirmation/failure, without blocking and without tearing down the connection.

Published Sep 2, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Go

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (high)+6
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Golang

Crypto and 1 more

CVSS base

7.5

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — go.dev (NIST National Vulnerability Database)
Documented patch — pkg.go.dev (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Golang Crypto, Golang.org/x/crypto Golang.org/x/crypto/ssh).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Golang	Crypto	< 0.56.0	Vulnerable	NIST National Vulnerability Database
Golang.org/x/crypto	Golang.org/x/crypto/ssh	< 0.56.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.5	CVSS 3.1	High	3.9	3.6	134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
7.5	CVSS 3.1	High	—	—	CISA-ADP via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (score shown at the top: 134c704f-9b21-4f2e-91b3-4a467353bcc0)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-770 · Allocation of Resources Without Limits or Throttling

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Track CPU/memory spikes and availability drops correlated with request patterns.

web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

2026
Affected products added · golang.org/x/crypto/golang.org/x/crypto/ssh
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
Fix documented
Oct 15, 2026 · NIST National Vulnerability Database
CVSS changed · 7.5
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 2, 2026 · Go

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

4 on the record

go.dev/issue/81316
Issue Tracking, Vendor Advisory, NIST National Vulnerability Database
groups.google.com/g/golang-announce/c/1y3fb2np35U
Mailing List, Vendor Advisory, NIST National Vulnerability Database
pkg.go.dev/vuln/GO-2026-6354
Patch, Vendor Advisory, NIST National Vulnerability Database
go.dev/cl/826504
Patch, NIST National Vulnerability Database

Elsewhere on this site

Golang
every CVE for this vendor

Denial of service
same class

CWE-770
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-56855 Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh Sep 2, 2026
High CVE-2026-56854 Source-address critical option not enforced for non-public-key auth callbacks in golang.org/x/crypto/ssh Aug 28, 2026
Medium CVE-2026-46598 Invoking pathological inputs can lead to client panic in golang.org/x/crypto/ssh/agent May 22, 2026
High CVE-2026-46597 Invoking byte arithmetic causes underflow and panic in golang.org/x/crypto/ssh May 22, 2026
Critical CVE-2026-42508 Invoking auth bypass via unenforced @revoked status in golang.org/x/crypto/ssh/knownhosts May 22, 2026
Critical CVE-2026-46595 Invoking VerifiedPublicKeyCallback permissions skip enforcement in golang.org/x/crypto/ssh May 22, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-78662 is "Prevent DoS on deadlocked undecided channel in golang.org/x/crypto/ssh", rated High. It affects Crypto (Golang); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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