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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

A flaw in goxmldsig can cause software to validate the wrong XML signature reference. An attacker able to submit signed XML may bypass integrity checks, allowing altered data to be trusted. The issue affects versions before 1.6.0 and is rated high severity.

Executive priority

Treat as a high-priority integrity issue where XML signatures establish trust or authorization. Inventory exposed services immediately and schedule an expedited upgrade to 1.6.0. Internet-facing identity, federation, transaction, or configuration workflows should receive first attention. Emergency incident response is not justified solely by this bundle because active exploitation is unconfirmed.

Technical view

In validateSignature, code takes the address of a range-loop variable while searching SignedInfo references. Under Go versions before 1.22, or older go.mod language semantics, the retained pointer can resolve to the final slice element instead of the intended match. This reference-selection error can bypass XML signature validation and compromise integrity.

Likely exposure

Exposure is most likely in network-accessible applications that use goxmldsig below 1.6.0 to validate attacker-controlled XML signatures. Priority increases where signature validity authorizes identity, transactions, configuration, or other trusted data. Actual exposure requires confirming the dependency version, Go module semantics, and whether untrusted XML reaches the affected validation path.

Exploitation context

The CVSS 3.1 score is 7.5: network-reachable, low complexity, no privileges, and no user interaction, with high integrity impact. The supplied record says this CVE is not in KEV, and the sources provide no evidence of active exploitation. Practical prerequisites and public exploit availability are not established in the bundle.

Researcher notes

The root cause maps to CWE-347 and CWE-682: signature verification is undermined by incorrect reference selection. Investigation should focus on reachability of validateSignature, multi-reference SignedInfo handling, duplicate ID matches, and build language semantics. The bundle does not establish exact application-level consequences, exploit prevalence, or whether every pre-1.6.0 deployment is practically exploitable.

Mitigation direction

  • Upgrade direct and transitive goxmldsig dependencies to version 1.6.0 or later.
  • Apply applicable Red Hat security errata for vendor-managed packages.
  • Temporarily restrict untrusted signed XML from reaching affected validation paths.
  • Review vendor guidance before relying on Go-version changes as a substitute for upgrading.

Validation and detection

  • Inspect dependency manifests, lockfiles, and built artifacts for goxmldsig versions below 1.6.0.
  • Confirm the deployed artifact contains goxmldsig 1.6.0 or later.
  • Identify every endpoint and workflow that validates externally supplied XML signatures.
  • Test reference selection with multiple references and verify the intended signed element is validated.
  • Record the Go toolchain and go.mod language version used for each affected build.
Prepared
Confidence
high
Sources
5

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.

Open ATT&CK lookup
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.

Open ATT&CK lookup
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