CVE-2026-46597: CVE-2026-46597: Remote Denial of Service in golang.org/x/crypto/ssh via AES-GCM Padding Integer Overflow

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CVE-2026-46597: Remote Denial of Service in golang.org/x/crypto/ssh via AES-GCM Padding Integer Overflow

Vulnerability ID: CVE-2026-46597
CVSS Score: 7.5
Published: 2026-06-25

A high-severity Denial of Service (DoS) vulnerability (CVE-2026-46597 / GO-2026-5013) exists in the golang.org/x/crypto/ssh module before version v0.52.0. The flaw stems from an incorrect operator order during a type conversion of the GCM packet padding size, allowing a remote, unauthenticated attacker to trigger an out-of-bounds slice runtime panic and crash the Go process.

TL;DR

Unauthenticated remote attackers can crash Go-based SSH servers or clients using AES-GCM ciphers by exploiting an integer overflow in padding length checks.

Technical Details

CWE ID: CWE-191 / CWE-704
Attack Vector: Network (AV:N)
CVSS v3.1 Score: 7.5 (High)
EPSS Score: 0.00359 (27.78% percentile)
Impact: Complete Denial of Service (A:H)
Exploit Status: Unproven / No Public PoC
CISA KEV Status: Not Listed

Affected Systems

golang.org/x/crypto/ssh
Docker
containerd
HashiCorp Vault
Gitea
Prometheus
AWS Systems Manager Agent (SSM)
cAdvisor
Podman
Trivy
golang.org/x/crypto: < v0.52.0 (Fixed in: v0.52.0)

Code Analysis

Commit: abbc44d

ssh: fix type conversion order during GCM padding validation to prevent overflow

diff --git a/ssh/cipher.go b/ssh/cipher.go
index ad2b370..48d0199 100644
--- a/ssh/cipher.go
+++ b/ssh/cipher.go
@@ -407,7 +407,7 @@
        return nil, fmt.Errorf("ssh: illegal padding %d", padding)
    }

-   if int(padding+1) >= len(plain) {
+   if int(padding)+1 >= len(plain) {
        return nil, fmt.Errorf("ssh: padding %d too large", padding)
    }
    plain = plain[1 : length-uint32(padding)]

Mitigation Strategies

Upgrade the golang.org/x/crypto module to version v0.52.0 or later and recompile downstream applications.
Disable AES-GCM cipher suites (aes128-gcm@openssh.com, aes256-gcm@openssh.com) in the SSH server and client configurations.

Remediation Steps:

Update your go.mod file: run 'go get golang.org/x/crypto@v0.52.0'
Run 'go mod tidy' to update dependency trees.
Rebuild and redeploy all affected services and container images.
Verify dependencies across downstream microservices using SCA tools.

References

Read the full report for CVE-2026-46597 on our website for more details including interactive diagrams and full exploit analysis.

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