Unknown

CVE-2026-111943 — Distrust compromised intermediate certificates in crypto/x509

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.

Published Oct 20, 2026 · Updated Oct 22, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Go

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.3%

ahead of 22% of scored CVEs · Oct 26, 2026

Affects

Go standard library

Crypto/x509

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Go standard library Crypto/x509).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Go standard library	Crypto/x509	< 1.26.10≥ 1.27.0-0 and < 1.27.3	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 21, 2026 → Oct 26, 2026 · 6 reading(s) · max 0.30%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Source status changed · Received → Awaiting Analysis
Oct 22, 2026 · NIST National Vulnerability Database
Record published
Oct 20, 2026
Affected products added · go standard library/crypto/x509
Oct 20, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 20, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 20, 2026 · Alertas do Telegram
CVE published
Oct 20, 2026 · Go

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 20, 2026 – Oct 20, 2026
1× Official description updated · Oct 20, 2026 – Oct 20, 2026

References

5 on the record

pkg.go.dev/vuln/GO-2026-6809
NIST National Vulnerability Database
www.openwall.com/lists/oss-security/2026/10/20/29
NIST National Vulnerability Database
go.dev/issue/82345
NIST National Vulnerability Database
groups.google.com/g/golang-announce/c/66pojueaQek
NIST National Vulnerability Database
go.dev/cl/851047
NIST National Vulnerability Database

Elsewhere on this site

Go standard library
every CVE for this vendor

Related CVEs (same products)

Medium CVE-2026-27145 Inefficient candidate hostname parsing in crypto/x509 Jun 2, 2026
High CVE-2026-33810 Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509 Apr 7, 2026
High CVE-2026-32281 Inefficient policy validation in crypto/x509 Apr 7, 2026
High CVE-2026-32280 Unexpected work during chain building in crypto/x509 Apr 7, 2026
High CVE-2026-27137 Incorrect enforcement of email constraints in crypto/x509 Mar 6, 2026
Medium CVE-2026-27138 Panic in name constraint checking for malformed certificates in crypto/x509 Mar 6, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-111943 is "Distrust compromised intermediate certificates in crypto/x509", rated Unknown. It affects Crypto/x509 (Go standard library); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.30% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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