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CVE Record

CVE-2026-33810: Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509

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.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysis

Security readout for executives and security teams

Some Go certificate validation can wrongly accept a trusted certificate chain when DNS name constraints exclude a domain but a wildcard DNS name uses different letter casing. This can weaken certificate-based trust boundaries, especially in environments using private PKI, constrained certificate authorities, mTLS, or custom trust pools. Exposure is most likely in Go applications or services that validate certificates using crypto/x509 and trust roots from a system pool or configured CertPool. Risk is higher where name-constrained subordinate CAs, private PKI, custom roots, or mTLS authorization boundaries are important. Treat as high priority for Go-based systems relying on certificate validation for access control or service identity. Patch planning should focus on internet-facing services, mTLS-heavy platforms, and environments using private or constrained CAs. Mitigation focus: Check Go advisory GO-2026-4866 and vendor guidance for fixed versions.; Apply Go toolchain, runtime, container, and OS vendor updates when available.; Inventory Go services that perform TLS, mTLS, or certificate chain validation..

Prepared

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-1289: Exact CWE lookup

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cwe · low confidence lookup

CWE-295: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-33810 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
41Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:L2.85.3redhat-SADP
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2026-33810Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container
redhat-SADPcrypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application
other:Red Hat severity ratingcvssV3_1
  • 2026-04-08T02:01:09.100Z: Reported to Red Hat.
  • 2026-04-08T01:06:56.546Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Go standard librarycrypto/x509crypto/x509, 1.26.0-0unaffected
Weakness

CWE details

CWE-1289CWE-295

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-1289 · source CWE mapping

Improper Validation of Unsafe Equivalence in Input

Improper Validation of Unsafe Equivalence in Input represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-295 · source CWE mapping

Improper Certificate Validation

Improper Certificate Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs