CVE-2026-56858: Fix Javascript regexp context tracking in html/template
CSIRTS triage
- What
- The html/template package has incorrect JavaScript regexp context tracking, potentially allowing XSS injection.
- Who is affected
- Go applications using html/template to generate HTML with embedded JavaScript from untrusted data.
- Urgency
- Medium severity (CVSS 6.1); context confusion in template escaping can lead to XSS; patch to fix escaping logic.
- Action
- Update Go to a patched version that correctly tracks JavaScript regexp context in html/template.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56858
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-568580.25% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 17% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-56858 | coverage & exploitation status | NVD · CVE.org |
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