What is the CVSS score of EUVD-2026-31397?

EUVD-2026-31397 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. EPSS exploitation probability: 0.0%.

Is there a public PoC exploit available for EUVD-2026-31397?

Yes, a public proof-of-concept exploit is available for EUVD-2026-31397. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate EUVD-2026-31397?

Within 24 hours: Inventory all Go applications and services using golang.org/x/crypto/ssh; identify production SSH infrastructure and assign patch owners. Within 7 days: Update golang.org/x/crypto to version 0.52.0 or later; test in staging environments and schedule production deployment windows. Within 30 days: Deploy patched versions to all production systems and monitor for service stability.

golang.org/x/crypto/ssh EUVD-2026-31397

Q: Which versions of golang.org/x/crypto/ssh are affected by EUVD-2026-31397?

A critical vulnerability in the Go SSH library (golang.org/x/crypto) threatens the availability of SSH-based infrastructure components including access controls, CI/CD systems, and remote…. A patch is available.

| CVE-2026-39830 CRITICAL

Buffer Overflow (CWE-119)

2026-05-22 Go

GHSA-vgwf-h737-ff37

Buffer Overflow Golang Org X Crypto Ssh Golang Org X Crypto

9.1

CVSS 3.1 · Vendor: Go

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Recon

Identify Go SSH client or server target
Delivery

Position attacker-controlled SSH peer
Exploit

Complete SSH transport handshake
Install

Send unsolicited global request responses
C2

Fill internal buffer and block read goroutine
Execute

Repeat across connections to exhaust resources
Impact

Denial of service via OOM or FD exhaustion

Vulnerability Assessment

Weakness	CWE CWE-119 ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, buffer size validation MITRE ATT&CK 2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	The vulnerable code path requires that an attacker-controlled SSH peer be able to send protocol messages to the target after a transport-level SSH connection is established - meaning either the target connects out to an attacker-controlled SSH server, or the target runs a Go SSH server reachable by the attacker. No authentication on the SSH layer is required because unsolicited global request responses are processed at the transport layer before or independent of userauth, matching the CVSS PR:N. The target must be running a Go binary that links golang.org/x/crypto/ssh at a version below 0.52.0 and must keep connections open long enough for the buffer to fill (a small fixed number of unsolicited responses). Limiting factors: the attacker needs network reachability to or from the Go SSH endpoint, impact is confined to availability of that process (no code execution or data disclosure path), and short-lived one-shot SSH clients that exit quickly are minimally affected because the leak does not outlive the process.
Impact	Signals here are sharply conflicting and require interpretation. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/C:H/I:N/A:H) yields 9.1 by treating availability impact as High and asserting confidentiality impact as High, but the described behavior is purely a resource leak with no data disclosure path - the C:H rating appears overstated and the real impact is availability-only (resource exhaustion). SSVC corroborates the more modest view: Exploitation 'none', Technical Impact 'partial', Automatable 'yes'. EPSS at 0.02% (4th percentile) and no entry on CISA KEV align with SSVC's 'none' exploitation finding. The realistic risk is a denial-of-service against long-lived Go SSH clients/servers reachable by an attacker who controls the peer endpoint - meaningful for bastions, CI runners, and SSH-based control planes, but not the critical-priority emergency the 9.1 number suggests. Treat as a medium-priority availability fix, prioritizing internet-exposed Go SSH services.
Exploit ScenarioDerived	An attacker stands up a malicious SSH endpoint (or compromises one) and waits for a vulnerable Go-based client - for example a Terraform provisioner, CI agent, or fleet management tool - to connect; upon completing the handshake, the attacker sends a stream of unsolicited global request responses that fill the client's internal buffer, blocking its read goroutine permanently. Repeating across many connections, or coercing the victim into reconnecting, accumulates leaked goroutines and memory until the process OOMs or exhausts file descriptors. No public exploit is identified at time of analysis, but the protocol-level trigger is trivial to script for anyone with an SSH library.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 02, 2026

Resource exhaustion in the Go golang.org/x/crypto/ssh package allows a malicious SSH peer to leak goroutines and memory by sending unsolicited global request responses that fill an internal buffer and block the connection's read loop. Affected versions are below 0.52.0, and even calling Close() fails to release the blocked goroutine, enabling per-connection resource leaks against any Go application using this library as an SSH client or server. There is no public exploit identified at time of analysis, and the EPSS score of 0.02% (4th percentile) indicates very low observed exploitation interest despite the high CVSS rating.

RemediationAI

Vendor-released patch: golang.org/x/crypto v0.52.0 - upgrade the module dependency with 'go get golang.org/x/crypto@v0.52.0' followed by 'go mod tidy', then rebuild and redeploy all binaries that embed the SSH stack (static linking means library updates alone do not fix already-shipped binaries). Run 'govulncheck ./...' to confirm GO-2026-5017 is no longer reported, and consult the upstream fix commits at https://go.dev/cl/781664 and https://go.dev/cl/781640, the issue tracker at https://go.dev/issue/79564, and the advisory at https://pkg.go.dev/vuln/GO-2026-5017. Where immediate rebuilds are not possible, compensating controls include restricting which SSH peers a Go-based client connects to via allowlists (limits operational flexibility), placing affected SSH servers behind a non-Go SSH proxy such as OpenSSH that terminates the protocol before the Go stack sees it (adds a hop and configuration burden), and aggressive connection idle timeouts plus process-level memory/FD limits and periodic restarts to bound the leak's blast radius (does not stop the underlying leak and may interrupt legitimate sessions).

Affected VersionsENISA

golang.org/x/crypto/ssh 0 <0.52.0

Affected Packages

go golang.org/x/crypto fix: 0.52.0

go golang.org/x/crypto/ssh fix: 0.52.0

euvd golang_org_x_crypto_ssh fix: 0.52.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 3 packages in go, euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability lives in the Go standard supplemental cryptography module golang.org/x/crypto/ssh, the dominant pure-Go SSH implementation used by tools like Terraform, Docker, Kubernetes operators, and countless DevOps utilities. Per CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), the SSH transport layer processes RFC 4254 global request messages and queues responses in a bounded internal channel; a malicious peer sending unsolicited global request *responses* (replies with no matching pending request) fills that channel, causing the goroutine that reads from the SSH transport to block indefinitely on a send. Because the read loop owns the lifecycle signaling for the connection, the blocked goroutine cannot be unwound by Close(), producing a per-connection resource leak of goroutines, memory, and file descriptors. The fix in 0.52.0 silently discards unsolicited global responses rather than buffering them.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (Go) PRIMARY 9.1 CRITICAL

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

SUSE CRITICAL

Red Hat 7.5 HIGH

Primary rating from Vendor (Go).

CVSS VectorVendor: Go

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Lifecycle Timeline

CVSS changed

Jun 02, 2026 - 16:37 NVD

9.1 (None) 9.1 (CRITICAL)

Patch available

May 22, 2026 - 04:31 EUVD

CVE Published

May 22, 2026 - 02:31 nvd

UNKNOWN (no severity yet)

DescriptionCVE.org

A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection's read loop. The blocked goroutine could not be released by calling Close(), resulting in a resource leak per connection. Unsolicited global responses are now discarded.

Executive ViewAI

Why It Matters

A critical vulnerability in the Go SSH library (golang.org/x/crypto) threatens the availability of SSH-based infrastructure components including access controls, CI/CD systems, and remote administration tools. Attackers can trigger resource exhaustion and service unavailability with simple connection attempts, affecting any organization with Go-deployed SSH services. While current exploitation remains minimal (EPSS 0.02%), the simplicity of attack and centrality of SSH to infrastructure access makes immediate patching essential.

Business Impact: High

Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score

0.0%

Top 96% exploitable

Threat Intel

1 sources

Exploit

POC

Public exploit code exists

Data Quality

8 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment GHSA MSRC Vendor

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC Yes

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

CRITICAL severity + public POC available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision

Scheduled

Exploitation

None

System Exposure· derived

Open

Automatable

Yes

Human Impact

High

Technical Impact

Partial

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +46

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Related Vulnerabilities in golang.org/x/crypto SSH Implementation Vulnerabilities

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7.5

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5.3

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9.1

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Source-address critical option enforcement in golang.org/x/crypto/ssh is incomplete, allowing remote attackers to bypass

Same weakness CWE-119 – Buffer Overflow

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CVE-2009-0927 HIGH POC

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8.8

Vendor StatusVendor

SUSE

Severity: Critical

Product	Status
openSUSE Leap 16.0	Fixed
openSUSE Tumbleweed	Fixed
SUSE Linux Enterprise Module for HPC 15 SP7	Affected
SUSE Linux Enterprise High Performance Computing 15 SP7	Affected
SUSE Linux Enterprise Server 15 SP6-LTSS	Affected

References

Advisories & patches

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