# CVE-2026-27138: Panic in name constraint checking for malformed certificates in crypto/x509

CVE-2026-27138 is fixed in 5 products on 2 platforms, first by Go Programming Language 1.26.1, released March 5, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-27138
- Priority: Routine
- CVSS: 5.9 (Moderate)
- EPSS: 0.0038
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 6, 2026
- Weakness: CWE-1285: Improper Validation of Specified Index, Position, or Offset in Input
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-27138

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Go Programming Language | 1.26.1 | [Go Programming Language 1.26.1](https://patchblox.com/security/data/fix/windows-app/golang.go-1.26.1.md) | Mar 5, 2026 |
| Linux | go1.26 opensuse-leap 15.6 | 1.26.1-150000.1.6.1 | [SUSE-SU-2026:0876-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0876-1.md) | Mar 11, 2026 |
| Linux | go1.26 opensuse-leap 16.0 | 1.26.1-160000.1.1 | [OPENSUSE-SU-2026:20342-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20342-1.md) | Mar 11, 2026 |
| Linux | go1.26 sles 15.6 | 1.26.1-150000.1.6.1 | [SUSE-SU-2026:0876-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0876-1.md) | Mar 11, 2026 |
| Linux | go1.26 sles 15.7 | 1.26.1-150000.1.6.1 | [SUSE-SU-2026:0876-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0876-1.md) | Mar 11, 2026 |
| Linux | go1.26-openssl opensuse-leap 15.6 | 1.26.1-150600.13.3.1 | [SUSE-SU-2026:0976-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0976-1.md) | Mar 23, 2026 |
| Linux | go1.26-openssl opensuse-leap 16.0 | 1.26.1-160000.1.1 | [OPENSUSE-SU-2026:20537-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20537-1.md) | Apr 14, 2026 |
| Linux | go1.26-openssl sles 15.6 | 1.26.1-150600.13.3.1 | [SUSE-SU-2026:0976-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0976-1.md) | Mar 23, 2026 |
| Linux | go1.26-openssl sles 15.7 | 1.26.1-150600.13.3.1 | [SUSE-SU-2026:0976-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0976-1.md) | Mar 23, 2026 |
| Linux | go1.26-openssl sles 16.0 | 1.26.1-160000.1.1 | [SUSE-SU-2026:21195-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-21195-1.md) | Apr 14, 2026 |
| Linux | golang-1.26 Debian 14 | 1.26.1-1 | [DEBIAN-CVE-2026-27138](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27138.md) | Mar 6, 2026 |
| Linux | govulncheck-vulndb opensuse-leap 15.6 | 0.0.20260317T205859-150000.1.152.1 | [SUSE-SU-2026:1042-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-1042-1.md) | Mar 25, 2026 |
| Linux | govulncheck-vulndb opensuse-leap 16.0 | 0.0.20260723T184607-160000.1.1 | [OPENSUSE-SU-2026:21483-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21483-1.md) | Jul 30, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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