validateSignature Loop Variable Capture Signature Bypass in goxmldsig

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-33487: 0.32% estimated exploitation activity in the next 30 days; percentile 25.27 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Details 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. ------ Technical Details The code takes the address of a loop iteration variable (&ref). In the standard Go compiler, this variable is only allocated once for the whole loop, so its address stays the same, but its value changes with each iteration. As a result, any pointer to this variable will always point to the value of the last element processed by the loop, no matter which element matched the search criteria. Using Radare2, I found that the…

Published by the source

18 Mar 2026, 20:18 UTC

Last modified by the source

27 Mar 2026, 20:58 UTC

Source last checked

26 Oct 2026, 15:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-479m-364c-43vc

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# Patch Next advisory brief: CVE-2026-33487

Advisory: validateSignature Loop Variable Capture Signature Bypass in goxmldsig
IDs: CVE-2026-33487, GHSA-479m-364c-43vc
Record: https://patchnext.com/advisories/cve-2026-33487 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/russellhaering/goxmldsig 1.6.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/russellhaering/goxmldsig: affected <= 1.5.0; fixed in 1.6.0

## Suggested inspection (read-only)
- Go github.com/russellhaering/goxmldsig: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/russellhaering/goxmldsig.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-479m-364c-43vc (GitHub-reviewed advisory GHSA-479m-364c-43vc lists affected ranges: Go github.com/russellhaering/goxmldsig >=0 <=1.5.0)

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