CVE-2026-56853: Apply ReadHeaderTimeout when doing unencrypted HTTP/2 check in net/http
CSIRTS triage
- What
- The net/http package does not apply ReadHeaderTimeout when checking for unencrypted HTTP/2, allowing slowloris-style denial of service.
- Who is affected
- Go HTTP/2 servers that accept unencrypted connections and do not configure ReadHeaderTimeout.
- Urgency
- High severity (CVSS 7.5); timeout bypass enables resource exhaustion attacks; apply patches immediately.
- Action
- Update Go to a patched version that applies ReadHeaderTimeout during unencrypted HTTP/2 checks.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56853
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-2026-568530.59% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 46% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-56853 | coverage & exploitation status | NVD · CVE.org |
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