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CVE Record

CVE-2026-33487: goxmldsig has validateSignature Loop Variable Capture Signature Bypass

goxmlsig provides XML Digital Signatures implemented in Go. Prior to version 1.6.0, the `validateSignature` function in `validate.go` goes through the references in the `SignedInfo` block to find one that matches the signed element's ID. In Go versions before 1.22, or when `go.mod` uses an older version, there is a loop variable capture issue. The code takes the address of the loop variable `_ref` instead of its value. As a result, if more than one reference matches the ID or if the loop logic is incorrect, the `ref` pointer will always end up pointing to the last element in the `SignedInfo.References` slice after the loop. goxmlsig version 1.6.0 contains a patch.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw can let software using goxmldsig accept an XML digital signature check incorrectly. In business terms, systems that rely on signed XML for trust decisions could treat tampered or unintended content as valid. The known fixed version is goxmldsig 1.6.0.

Executive priority

Treat as high priority for systems where XML signature validation protects identity, authorization, or transaction integrity. Patch affected dependencies promptly, but avoid emergency assumptions about exploitation because the supplied sources do not show active abuse.

Technical view

Before goxmldsig 1.6.0, validateSignature can capture the address of a loop variable while selecting SignedInfo references. Under older Go loop semantics, the selected reference pointer may resolve to the last reference, enabling a signature validation bypass. The CVSS 3.1 score is 7.5 with high integrity impact.

Likely exposure

Exposure is most likely in Go applications or vendor products that import github.com/russellhaering/goxmldsig below 1.6.0 and validate XML signatures for authentication, authorization, SAML-like assertions, or document integrity.

Exploitation context

The source bundle does not show CISA KEV listing or other evidence of active exploitation. The issue is remotely relevant where attackers can submit signed XML to affected validation code, but no exploit steps are provided in the cited sources.

Researcher notes

The core bug is loop variable address capture in validate.go during SignedInfo reference selection. Go 1.22 loop semantics matter, but the source names goxmldsig before 1.6.0 as affected and 1.6.0 as patched.

Mitigation direction

  • Upgrade goxmldsig to version 1.6.0 or later.
  • Check vendor advisories for Red Hat-packaged affected components.
  • Prioritize systems where XML signatures drive trust or access decisions.
  • Rebuild and redeploy applications after dependency updates.
  • If unable to upgrade, seek vendor guidance for supported mitigations.

Validation and detection

  • Inventory direct and transitive uses of github.com/russellhaering/goxmldsig.
  • Flag versions older than 1.6.0 in Go dependency manifests.
  • Identify services that accept externally supplied signed XML.
  • Confirm runtime builds use the remediated dependency version.
  • Review Red Hat VEX and RHSA entries for package-specific status.
Prepared
Confidence
high
Sources
12

Public sources used

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-347: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · low confidence lookup

CWE-682: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-33487 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

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
2ADP providers
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: 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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-33487Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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
other:ssvc
redhat-SADPgithub.com/russellhaering/goxmldsig: goxmlsig: Integrity bypass due to incorrect XML Digital Signature validation via loop variable capture issue
other:Red Hat severity ratingcvssV3_1
  • 2026-03-26T18:02:32.278Z: Reported to Red Hat.
  • 2026-03-26T17:17:51.101Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
russellhaeringgoxmldsig< 1.6.0Listed
Weakness

CWE details

CWE-347CWE-682

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

CWE-347 · source CWE mapping

Improper Verification of Cryptographic Signature

Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-682 · source CWE mapping

Incorrect Calculation

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

Open CWE intelligenceSame-CWE CVEs