01 Record

CVE-2026-56855

Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh

HighPUBLISHEDCNA: Go

CNA base score7.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

View raw JSON

02 Description

Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.50% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 42.5% of scored records. A rank, not a probability.

NVD base score

7.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-09-04.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-09-02 19:37Z1 MO AGO

Last updated

2026-09-03 14:14Z1 MO AGO

Reserved

2026-06-23

Assigning CNA

Record state

PUBLISHED

Severity

High (CVSS 7.5)

CNA CVSS vector

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

Weaknesses

CWE-770Allocation of Resources Without Limits or ThrottlingBase
CWE-833DeadlockBase

Data version

5.2

Document digest

2254b158c6dffa44cc35ee7be334aa5cac66ee0518e8ca9d026e04068fb0e58c

05 Affected products

VendorProductVersionsPlatforms

golang.org/x/cryptogolang.org/x/crypto/ssh0 to < 0.56.0—

06 References

go.devhttps://go.dev/issue/81317
go.devhttps://go.dev/cl/826524
groups.google.comhttps://groups.google.com/g/golang-announce/c/1y3fb2np35U
pkg.go.devhttps://pkg.go.dev/vuln/GO-2026-6355

07 Fixed in

AlmaLinux 9

buildah
Fixed

A version is affected if any line below covers it.
- Affected before 2:1.43.3-2.el9_8
- Affected before 2:1.43.4-2.el9_8
buildah-tests
Fixed

A version is affected if any line below covers it.
- Affected before 2:1.43.3-2.el9_8
- Affected before 2:1.43.4-2.el9_8

CloudLinux 9

buildah
Fixed

A version is affected if any line below covers it.
- Affected before 2:1.43.3-2.el9_8
- Affected before 2:1.43.4-2.el9_8
buildah-tests
Fixed

A version is affected if any line below covers it.
- Affected before 2:1.43.3-2.el9_8
- Affected before 2:1.43.4-2.el9_8

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Debian 12

golang-go.crypto
No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

golang-go.crypto
No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

golang-go.crypto
Fixed in 1:0.56.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.