Security Digest · Vulnerability record
CVE-2026-111943: Distrust compromised intermediate certificates in crypto/x509
On most platforms, Go uses the given system root certificates.
EPSS 0.1% · p3 Patch this week Patch this week
Should you act?
Normal patch cycle
No exploitation signal; fix it in your next routine update if you are affected. 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. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.1%, percentile 3: FIRST’s model estimates a 0.1% chance of exploitation activity in the next 30 days, higher than 3% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Editorial verdict: Patch this week. eMudhra CA Key Compromise: Update Non-Browser TLS Clients — Anyone can mint certificates from these broken CA keys, but only clients that skip Certificate Transparency and still trust the emSign root are exposed, and only to an on-path attacker: update those trust bundles this week, build machines first.
- Editorial verdict: Patch this week. Go October 2026 Security Releases: 16 Stdlib Fixes — Rebuild and redeploy Go services with Go 1.27.3 or 1.26.10 this week, starting with internet-facing HTTP/2 servers and reverse proxies; none of these bugs is known to be exploited.
What it is
On most platforms, Go uses the given system root certificates. However, in some narrower cases, the system trust stores may not be updated without further action. To defend against the narrower set of cases that may remain affected, a denylist was added in crypto/x509 to return an error when calling Verify with any of the known intermediate certificates that are no longer considered to be trustworthy.
Product: Go standard library crypto/x509 · Assigned by: Go · Published: 2026-10-21
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Go standard library | crypto/x509 | < 1.26.10, 1.27.0-0 < 1.27.3 |
Severity scores
No CVSS score has been published for this CVE yet.
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).
- FIRST EPSS (model of 2026-10-21): 0.14% probability of exploitation activity in the next 30 days; percentile 3.
Timeline
- — erroneo.us brief: Go October 2026 Security Releases: 16 Stdlib Fixes
- — erroneo.us brief: eMudhra CA Key Compromise: Update Non-Browser TLS Clients
- — CVE record last updated
- — CVE record published by Go
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- CVE.org record CVE-2026-111943 cve.org
- NVD entry CVE-2026-111943 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
- openwall.com openwall.com