CVE-2026-27138— Panic in name constraint checking for malformed certificates in crypto/x509
Quick assessment
Affected
Go standard library crypto/x509
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Google Go是美国谷歌（Google）公司的一种静态强类型、编译型、并发型，并具有垃圾回收功能的编程语言。 Google Go存在安全漏洞，该漏洞源于证书链中证书具有空DNS名称且另一证书具有排除名称约束时，证书验证可能崩溃，可能导致直接验证X.509证书链或使用TLS的程序崩溃。
Possible ATT&CK Techniques 1 AI
T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-27138
Vulnerability Information
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Vulnerability Title
Panic in name constraint checking for malformed certificates in crypto/x509
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Google Go 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Google Go是美国谷歌（Google）公司的一种静态强类型、编译型、并发型，并具有垃圾回收功能的编程语言。 Google Go存在安全漏洞，该漏洞源于证书链中证书具有空DNS名称且另一证书具有排除名称约束时，证书验证可能崩溃，可能导致直接验证X.509证书链或使用TLS的程序崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Go standard library | crypto/x509 | 1.26.0-0 ~ 1.26.1 | - |
|
II. Public POCs for CVE-2026-27138
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-27138 (1)
Vendor Advisories for CVE-2026-27138 (1)
News Coverage for CVE-2026-27138 (1)
Vendor Pages for CVE-2026-27138 (1)
Same Patch Batch · Go standard library · 2026-03-06 · 5 CVEs total
| CVE-2026-25679 | Incorrect parsing of IPv6 host literals in net/url | |
| CVE-2026-27137 | Incorrect enforcement of email constraints in crypto/x509 | |
| CVE-2026-27142 | URLs in meta content attribute actions are not escaped in html/template | |
| CVE-2026-27139 | FileInfo can escape from a Root in os |
IV. Related Vulnerabilities
Same product: crypto/x509
-
CVE-2026-27145
Inefficient candidate hostname parsing in crypto/x509 -
CVE-2026-32280
Unexpected work during chain building in crypto/x509 -
CVE-2026-32281
Inefficient policy validation in crypto/x509 -
CVE-2026-33810
Case-sensitive excludedSubtrees name constraints cause Auth -
CVE-2026-27137
Incorrect enforcement of email constraints in crypto/x509
Same vendor: Go standard library
-
CVE-2026-56860
Avoid quadratic complexity in resolvePath in net/url -
CVE-2026-56859
Add recursion depth guard during decode in encoding/xml -
CVE-2026-33818
Enforce maximum recursion depth in encoding/asn1 -
CVE-2026-56853
Apply ReadHeaderTimeout when doing unencrypted HTTP/2 check -
CVE-2026-56862
Limit handshake messages we are willing to accept post-hands
V. Comments for CVE-2026-27138
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