CVE-2026-39829 — x/crypto
HIGHCVE-2026-39829 is a high-severity (CVSS 7.5) CWE-347 vulnerability in golang.org/x/crypto. A fix is available for golang.org/x/crypto — see the affected versions and patch details below.
Invoking pathological RSA/DSA parameters may cause DoS in golang.org/x/crypto/ssh
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39829.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-39829 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
golang.org/x/cryptoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | golang.org/x/crypto | all versions | 0.52.0go get golang.org/x/crypto@v0.52.0 |
Affected Products
cryptogolangDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for golang.org/x/crypto, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update golang.org/x/crypto to 0.52.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39829 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability in golang.org/x/crypto/ssh is rated as Important. An unauthenticated remote attacker could trigger a denial of service by providing a specially crafted public key with excessively large parameters during SSH public key authentication. This could lead to prolonged CPU consumption on the server,…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for CVE-2026-39829 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 4 on RHEL 9 | cryostat/cryostat-storage-rhel9:4.2.0-19 | RHSA-2026:48151 |
| Red Hat Enterprise Linux 10 | buildah-2:1.43.1-3.el10_2 | RHSA-2026:36199 |
| Red Hat Enterprise Linux 10 | podman-7:5.8.2-4.el10_2 | RHSA-2026:37072 |
| Red Hat Enterprise Linux 8 | container-tools:rhel8-8100020260701102925.afee755d | RHSA-2026:35833 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | container-tools:rhel8-8080020260721142025.63b34585 | RHSA-2026:49944 |
| Red Hat Enterprise Linux 9 | buildah-2:1.43.1-2.el9_8 | RHSA-2026:29455 |
| Red Hat Enterprise Linux 9 | podman-6:5.8.2-4.el9_8 | RHSA-2026:37123 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | podman-5:5.4.0-22.el9_6.5 | RHSA-2026:67450 |
Frequently Asked Questions
Is CVE-2026-39829 in your dependencies?
Find it across Go, including transitive dependencies.