CVE-2026-39833 — x/crypto
CRITICALCVE-2026-39833 is a critical-severity (CVSS 9.1) CWE-862 vulnerability in golang.org/x/crypto. A fix is available for golang.org/x/crypto — see the affected versions and patch details below.
Invoking key constraints not enforced in golang.org/x/crypto/ssh/agent
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-39833.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-39833 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 389,824 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 in-memory keyring returned by NewKeyring() silently accepted keys with the ConfirmBeforeUse constraint but never enforced it. The key would sign without any confirmation prompt, with no indication to the caller that the constraint was not in effect. NewKeyring() now returns an error when unsupported constraints are requested.
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-2026-39833 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
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.
Red Hat rates this issue as Moderate with RH CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N). A flaw was found in golang.org/x/crypto/ssh/agent where the in-memory keyring returned by NewKeyring() silently accepted SSH agent keys with the ConfirmBeforeUse constraint but did not enforce interactive confirmation…
Update affected Go applications to use golang.org/x/crypto version 0.52.0 or later, which rejects unsupported ConfirmBeforeUse keys instead of silently ignoring the constraint. As a workaround, do not add keys with ConfirmBeforeUse to the in-memory keyring from golang.org/x/crypto/ssh/agent, or use an SSH agent implementation that correctly enforces confirm-before-use.Source: Red Hat security advisory for CVE-2026-39833 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cert Manager support for Red Hat OpenShift release 1.17 | cert-manager/jetstack-cert-manager-acmesolver-rhel9:1791371080 | RHSA-2026:82304 |
| Cert Manager support for Red Hat OpenShift release 1.17 | cert-manager/cert-manager-operator-rhel9:1791788287 | RHSA-2026:82322 |
| multicluster engine for Kubernetes 2.11 | multicluster-engine/hypershift-addon-rhel9-operator:1786912006 | RHSA-2026:57194 |
| OpenShift API for Data Protection 1.5 | oadp/oadp-mustgather-rhel9:1788859896 | RHSA-2026:66022 |
| OpenShift API for Data Protection 1.6 | oadp/oadp-velero-rhel9:1784058822 | RHSA-2026:43692 |
| Red Hat OpenShift Builds 1.7.3 | openshift-builds/openshift-builds-controller-rhel9:1783057515 | RHSA-2026:36648 |
| Red Hat OpenShift Builds 1.8.1 | openshift-builds/openshift-builds-controller-rhel9:1783612432 | RHSA-2026:41036 |
| Red Hat Openshift Data Foundation 4.22 | odf4/cephcsi-rhel9:1782932114 | RHSA-2026:37387 |
Frequently Asked Questions
Is CVE-2026-39833 in your dependencies?
Find it across Go, including transitive dependencies.