CVE-2026-33487 — goxmldsig
HIGHCVE-2026-33487 is a high-severity (CVSS 7.5) CWE-347 vulnerability in github.com/russellhaering/goxmldsig. A fix is available for github.com/russellhaering/goxmldsig — see the affected versions and patch details below.
goxmldsig has validateSignature Loop Variable Capture Signature Bypass
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33487.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-33487 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/russellhaering/goxmldsigReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/russellhaering/goxmldsig | all versions | 1.6.0go get github.com/russellhaering/goxmldsig@v1.6.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/russellhaering/goxmldsig, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/russellhaering/goxmldsig to 1.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33487 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33487 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33487. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Multicluster Global Hub 1.3.4 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779212259 | RHSA-2026:22423 |
| Multicluster Global Hub 1.4.5 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779579439 | RHSA-2026:22347 |
| Multicluster Global Hub 1.6.5 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1780167118 | RHSA-2026:23345 |
| Red Hat Advanced Cluster Management for Kubernetes 2.14 | rhacm2/acm-grafana-rhel9:1782693386 | RHSA-2026:36882 |
| Red Hat Advanced Cluster Management for Kubernetes 2.15 | rhacm2/acm-grafana-rhel9:1777142269 | RHSA-2026:13548 |
| Red Hat multicluster global hub 1.5.3 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1778867753 | RHSA-2026:21769 |
| Red Hat OpenShift GitOps 1.18 | openshift-gitops-1/dex-rhel8:1779116359 | RHSA-2026:20946 |
| Red Hat OpenShift GitOps 1.19 | openshift-gitops-1/dex-rhel8:1779209965 | RHSA-2026:20943 |
Frequently Asked Questions
Is CVE-2026-33487 in your dependencies?
O3 Security finds CVE-2026-33487 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.