Security Digest · Vulnerability record
CVE-2026-39833: golang.org/x/crypto doesn't enforce invoking key constraints
The in-memory keyring returned by NewKeyring() silently accepted keys with the ConfirmBeforeUse constraint but never enforced it.
CVSS 9.1 Critical EPSS 0.5% · p41
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5%, percentile 41: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 41% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
golang.org/x/crypto(Go) < 0.52.0, fixed in 0.52.0. Check your lockfile, including transitive dependencies.
What it is
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.
From the GitHub advisory
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.
Weakness type: CWE-862.
Product: golang.org/x/crypto (Go) · Assigned by: Go · Published: 2026-05-22
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Go | golang.org/x/crypto | < 0.52.0 | 0.52.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| golang.org/x/crypto | golang.org/x/crypto/ssh/agent | < 0.52.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADP | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.49% probability of exploitation activity in the next 30 days; percentile 41.
Timeline
- — CVE record published by Go
- — GitHub-reviewed advisory GHSA-jppx-rxg9-jmrx published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-jppx-rxg9-jmrx github.com
- CVE.org record CVE-2026-39833 cve.org
- NVD entry CVE-2026-39833 nvd.nist.gov
Other references from the CVE record and advisory
- go.dev go.dev
- go.dev go.dev
- groups.google.com groups.google.com
- pkg.go.dev pkg.go.dev
- go.dev go.dev
- go.dev go.dev