CVE-2026-33810 — Improper Validation of Unsafe Equivalence in Input in Standard Library Crypto X509

CWE-1289 — Improper Validation of Unsafe Equivalence in Input10 documents8 sources
Severity
7.5HIGHNVD
EPSS
0.0%
top 98.78%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
GO Standard Library Crypto X509
Timeline
PublishedApr 8
Latest updateApr 9

Description

When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NExploitability: 3.9 | Impact: 3.6

Affected Packages1 packages

▶CVEListV5go_standard_library/crypto_x5091.26.0-0 — 1.26.2

🔴Vulnerability Details

4
OSV
CVE-2026-33810: When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a d↗2026-04-08
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GHSA
GHSA-fv83-x2xw-2j55: When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a d↗2026-04-08
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CVEList
Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509↗2026-04-08
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OSV
Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509↗2026-04-07
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📋Vendor Advisories

2
Red Hat
crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application↗2026-04-08
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Debian
CVE-2026-33810: golang-1.15 - When verifying a certificate chain containing excluded DNS constraints, these co...↗2026
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🕵️Threat Intelligence

1
Wiz
CVE-2026-33810 Impact, Exploitability, and Mitigation Steps | Wiz↗
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💬Community

2
Bugzilla
CVE-2026-33810 golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application [fedora-all]↗2026-04-09
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Bugzilla
CVE-2026-33810 crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application↗2026-04-08
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CVE-2026-33810 — HIGH severity | cvebase