golang.org/x/crypto/ssh: Improper Verification of Cryptographic Signature
CVE-2026-39829 is a high-severity improper verification of cryptographic signature vulnerability in golang.org/x/crypto/ssh from Golang.org/x/crypto, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 0.52.0 as the first without the flaw, so updating golang.org/x/crypto/ssh to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.47% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update golang.org/x/crypto/ssh to 0.52.0 or a later version.
- Read the advisory on pkg.go.dev for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE; 35 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CISA (ADP) |
| CVSS 3.1 | 7.5 | High | CNA |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Verification of Cryptographic Signature
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
More Improper Verification of Cryptographic Signature vulnerabilities (CWE-347)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other references
- go.dev/cl/781641Issue Tracking
- go.dev/cl/781661Issue Tracking
- go.dev/issue/79565Issue Tracking
- groups.google.com/g/golang-announce/c/a082jnz-LvIMailing List
- access.redhat.com/errata/RHSA-2026:26546
- access.redhat.com/errata/RHSA-2026:26547
- access.redhat.com/errata/RHSA-2026:29455
- access.redhat.com/errata/RHSA-2026:35833
- access.redhat.com/errata/RHSA-2026:36199
- access.redhat.com/errata/RHSA-2026:36207
- access.redhat.com/errata/RHSA-2026:36319
- access.redhat.com/errata/RHSA-2026:36625
- access.redhat.com/errata/RHSA-2026:36648
- access.redhat.com/errata/RHSA-2026:36651
- access.redhat.com/errata/RHSA-2026:36796
Other vulnerabilities in golang.org/x/crypto/ssh
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.1 High severity
- 7.5 High severity
- 9.1 Critical severity
Recent Improper Verification of Cryptographic Signature vulnerabilities
- 7.5 High severity
- 7.0 High severity
- 8.1 High severity
- 8.0 High severity
- 9.1 Critical severity
- 9.1 Critical severity
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