Panic in name constraint checking for malformed certificates in crypto/x509
Priority LOW 27CWE-295Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Spoofing
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 3 fixed, 8 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-295.
Summary
Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00382 32nd percentileScored 2026-11-07
Fix Partial crypto/x509 (Go standard library): 1.26.1Red Hat: 3 advisoriesRed Hat: 3 fixed, 8 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Go standard library | crypto/x509 | 1.26.0-0 to before 1.26.1 | 1.26.1 | Patch available | CNA |
- crypto/x509 VendorGo standard library Affected 1.26.0-0 to before 1.26.1 Fixed in 1.26.1 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:golang:go:1.26.0:*:*:*:*:*:*:* | 1.26.0 | Vulnerable | Go standard library |
- cpe:2.3:a:golang:go:1.26.0:*:*:*:*:*:*:* Versions 1.26.0 Vulnerable ·Go standard library
Remediation
- Fix · CNA crypto/x509 (Go standard library) Fixed in 1.26.1
Red Hat 3 advisories
- RHSA-2026:91249 Released 2026-10-27 · Red Hat rating CriticalRed Hat AI Base Images 3.5.5 (Neuron)
- Red Hat OpenShift AI 3.5 registry.redhat.io/rhai/base-image-neuron-rhel9
- RHSA-2026:91248 Released 2026-10-27 · Red Hat rating CriticalRed Hat AI Base Images 3.4.6 (Neuron)
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhai/base-image-neuron-rhel9
- RHSA-2026:7291 Released 2026-04-09 · Red Hat rating ImportantRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images golang1.26-1.26.2-1.hum1@aarch64, golang1.26-1.26.2-1.hum1@src, golang1.26-1.26.2-1.hum1@x86_64 +12
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Go standard library crypto/x509 1.26.1
2 records Highest priority Priority MEDIUM 1 MEDIUM, 1 LOW
Other records, highest priority first
- TI-2026-21587 Incorrect enforcement of email constraints in crypto/x509Priority MEDIUM 40
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| OpenShift Service Mesh 2 | Affected | No fix yet: Fix deferred |
| OpenShift Service Mesh 3 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Red Hat Hardened Images | Fixed | RHSA-2026:7291 |
| Red Hat OpenShift AI 3.4 | Fixed | RHSA-2026:91248 |
| Red Hat OpenShift AI 3.5 | Fixed | RHSA-2026:91249 |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-27138
- 2026-10-03 Alias added: GHSA-ph5j-38mg-j6hp
- 2026-10-30 Fix available: RHSA-2026:91248 · Red Hat
- 2026-10-30 Fix available: RHSA-2026:91249 · Red Hat
- 2026-10-30 Fix available: Red Hat OpenShift AI 3.4, Red Hat OpenShift AI 3.5 · Red Hat
References
More Go standard library Go vulnerabilities
- TI-2020-00578 Improper certificate validation in Microsoft Windows KEVCVSS 3.1HIGH 8.1
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2018-05208 The "go get" implementation in Go 1.9.4, when the -insecure command-line option is used… CVSS 3.1HIGH 8.8
- TI-2018-12083 Improper input validation in [UNKNOWN] golang CVSS 3.1HIGH 8.1
- TI-2024-16306 Mishandling of corrupt central directory record in archive/zip CVSS 3.1MEDIUM 5.5
- TI-2021-15910 Go before 1.16.9 and 1.17.x before 1.17.2 has a Buffer Overflow via large arguments in a… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-27138 · CVE Program
- CVE-2026-27138 · NVD
- FIRST EPSS
- GHSA-ph5j-38mg-j6hp · GitHub Advisory Database · CC BY 4.0
- CVE-2026-27138 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences