GHSA-w879-237q-wc7r CVE-2026-39829 GO-2026-5018

golang.org/x/crypto: Invoking pathological RSA/DSA parameters may cause DoS

High Go

Severity: 7.5 / 10; High · CVSS 3.1
Exploit chance (EPSS): 0.47%; Chance of exploitation in the next 30 days. Higher than 40.44% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-347 Improper Verification of Cryptographic Signature; CWE-1284 Improper Validation of Specified Quantity in Input
Fix: 0.52.0; Upgrade golang.org/x/crypto to this version or later

Description

The RSA and DSA public key parsers did not enforce size limits on key parameters. A crafted public key with an excessively large modulus or DSA parameter could cause several minutes of CPU consumption during signature verification. This could be triggered by unauthenticated clients during public key authentication. RSA moduli are now limited to 8192 bits, and DSA parameters are validated per FIPS 186-2.

Affected versions

Go

Package	Vulnerable	Fixed in
golang.org/x/crypto	`< 0.52.0`	`0.52.0`
golang.org/x/crypto	`< 0.52.0`	`0.52.0`

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 → `0.52.0`

go

go get golang.org/x/crypto@v0.52.0 && 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-347: Improper Verification of Cryptographic Signature

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

CWE-1284: Improper Validation of Specified Quantity in Input

The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.

How to prevent it

Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

References

Advisories

Packages

cs.opensource.google/go/x/crypto

Timeline

May 22, 2026 Published
Sep 16, 2026 Last updated by the source
Oct 31, 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-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
GHSA-qpw4-5x99-6vjp golang.org/x/crypto: Invoking memory leak when rejecting channels can lead to DoS	Medium	Also affects golang.org/x/crypto

Credits: NCC Group Cryptography Services, sponsored by Teleport

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