What is the CVSS score of CVE-2026-39827?

CVE-2026-39827 has a CVSS 3.1 base score of 6.5 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.0%.

Is there a public PoC exploit available for CVE-2026-39827?

Yes, a public proof-of-concept exploit is available for CVE-2026-39827. Prioritise patching immediately. EPSS: 0.0%.

Is there a patch available for CVE-2026-39827?

Yes, a patch is available for CVE-2026-39827. Update the affected software to the latest version immediately.

Go x/crypto SSH CVE-2026-39827

EUVD-2026-31392 MEDIUM

Improper Enforcement of Message Integrity During Transmission (CWE-924)

2026-05-22 Go

GHSA-qpw4-5x99-6vjp

Denial Of Service Golang Org X Crypto Ssh Red Hat

6.5

CVSS 3.1 · Vendor: Go

Severity by source

Vendor (Go) PRIMARY

6.5 MEDIUM

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

SUSE

MEDIUM

qualitative

Red Hat

6.5 MEDIUM

qualitative

Primary rating from Vendor (Go).

CVSS VectorVendor: Go

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Jun 08, 2026 - 12:40 vuln.today

CVSS changed

May 26, 2026 - 18:07 NVD

6.5 (None) 6.5 (MEDIUM)

Patch available

May 22, 2026 - 04:31 EUVD

CVE Published

May 22, 2026 - 02:31 nvd

UNKNOWN (no severity yet)

DescriptionCVE.org

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.

AnalysisAI

Unbounded memory growth in the golang.org/x/crypto/ssh package allows an authenticated remote attacker to crash the SSH server process by repeatedly opening channels that the server rejects. All versions of golang.org/x/crypto/ssh prior to 0.52.0 are affected, and a successful attack disrupts service for every user connected to that server instance. No public exploit has been identified at time of analysis, and EPSS probability sits at 0.02% (5th percentile), though the authentication barrier is low and the availability impact affects all concurrent sessions.

Technical ContextAI

The affected component is golang.org/x/crypto/ssh (CPE: cpe:2.3:a:golang.org/x/crypto:golang.org/x/crypto/ssh:*:*:*:*:*:*:*:*), which is Go's extended cryptography library providing SSH client and server primitives. SSH supports channel multiplexing over a single connection (RFC 4254 §5), allowing multiple logical channels to share one transport. The root cause is classified as CWE-924 (Improper Enforcement of Message Integrity During Transmission in a Communication Channel): when a server rejects a channel-open request from an authenticated client, the rejected channel object is not removed from the connection's internal tracking state and is not released for garbage collection. Each rejection therefore leaks a reference, causing heap memory to grow without bound until the Go runtime cannot continue and the server process crashes. The fix, referenced in the upstream code review at go.dev/cl/781320 and tracked as GO-2026-5016, ensures rejected channels are properly purged from connection state.

RemediationAI

Upgrade golang.org/x/crypto to version 0.52.0 or later, which contains the authoritative fix (go.dev/cl/781320 and go.dev/issue/35127). Developers should run 'go get golang.org/x/crypto@v0.52.0' and rebuild all affected binaries; applications that embed the SSH server must be redeployed with the patched binary. The full announcement is available at the golang-announce mailing list (groups.google.com/g/golang-announce/c/a082jnz-LvI). For deployments where an immediate upgrade is not feasible, a targeted compensating control is to enforce strict per-user channel limits at the network or SSH daemon configuration layer (e.g., a reverse proxy or network policy that limits connection rate or channel count from a given authenticated identity), though this does not eliminate the memory leak - it only slows its progression. Restricting SSH access to a minimal set of trusted accounts reduces the attack surface, since exploitation requires valid credentials. SUSE-based environments should additionally consult SUSE advisories for patched package versions.