GHSA-8c26-wmh5-6g9v CVE-2022-27191 GO-2021-0356

golang.org/x/crypto/ssh Denial of service via crafted Signer

High Go

Severity: 7.5 / 10; High · CVSS 3.1
Exploit chance (EPSS): 3.93%; Chance of exploitation in the next 30 days. Higher than 90.37% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-327 Use of a Broken or Risky Cryptographic Algorithm
Fix: 0.0.0-20220314234659-1baeb1ce4c0b; Upgrade golang.org/x/crypto to this version or later

Description

The golang.org/x/crypto/ssh package before 0.0.0-20220314234659-1baeb1ce4c0b for Go allows an attacker to crash a server in certain circumstances involving AddHostKey.

Affected versions

Go

Package	Vulnerable	Fixed in
golang.org/x/crypto	`< 0.0.0-20220314234659-1baeb1ce4c0b`	`0.0.0-20220314234659-1baeb1ce4c0b`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

golang.org/x/crypto Go → `0.0.0-20220314234659-1baeb1ce4c0b`

go

go get golang.org/x/crypto@v0.0.0-20220314234659-1baeb1ce4c0b && go mod tidy

Severity breakdown

CVSS 3.1 7.5

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Weakness

CWE-327: Use of a Broken or Risky Cryptographic Algorithm

The product uses a broken or risky cryptographic algorithm or protocol.

How to prevent it

Architecture and Design: When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations. As with all cryptographic mechanisms, the source code should be available for analysis. For example, US government systems require FIPS 140-2 certification [REF-1192]. Do not develop custom or private cryptographic algorithms. They will likely be exposed to attacks that are well-understood by cryptographers. Reverse engineering techniques are mature. If the algorithm can be compromised if attackers find out how it works, then it is especially weak. Periodically ensure that the cryptography has not become obsolete. Some older algorithms, once thought to require a billion years of computing time, can now be broken in days or hours. This includes MD4, MD5, SHA1, DES, and other algorithms that were once regarded as strong. [REF-267]
Architecture and Design: Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms. With hardware, design the product at the Intellectual Property (IP) level so that one cryptographic algorithm can be replaced with another in the next generation of the hardware product.
Architecture and Design: Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. Industry-standard implementations will save development time and may be more likely to avoid errors that can occur during implementation of cryptographic algorithms. Consider the ESAPI Encryption feature.
Implementation, Architecture and Design: When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.

References

Advisories

Packages

cs.opensource.google/go/x/crypto

Timeline

Mar 18, 2022 Published
Sep 10, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GO-2026-6355 Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh	High	Also affects golang.org/x/crypto
GO-2026-6354 Prevent DoS on deadlocked undecided channel in golang.org/x/crypto/ssh	High	Also affects golang.org/x/crypto
GO-2026-6303 Source-address critical option not enforced for non-public-key auth callbacks in golang.org/x/crypto/ssh	High	Also affects golang.org/x/crypto
GO-2026-5932 The golang.org/x/crypto/openpgp package is unmaintained, unsafe by design, and has known security issues	Not rated yet	Also affects golang.org/x/crypto
GHSA-x527-x647-q7gg golang.org/x/crypto: Invoking VerifiedPublicKeyCallback permissions skip enforcement	Critical	Also affects golang.org/x/crypto
GHSA-w879-237q-wc7r golang.org/x/crypto: Invoking pathological RSA/DSA parameters may cause DoS	High	Also affects golang.org/x/crypto
GHSA-vgwf-h737-ff37 golang.org/x/crypto: Invoking client can cause server deadlock on unexpected responses	Critical	Also affects golang.org/x/crypto
GHSA-rm3j-f69w-wqmq golang.org/x/crypto vulnerable to infinite loop on large channel writes	Critical	Also affects golang.org/x/crypto

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