CVE-2026-65624: Cowboy HTTP/1.1 max_headers Bypass via Duplicate Header Names Enables Memory Exhaustion
CSIRTS triage
- What
- HTTP/1.1 max_headers limit can be bypassed using duplicate header names, enabling memory exhaustion.
- Who is affected
- Applications using Cowboy HTTP server without patched max_headers enforcement.
- Urgency
- Unknown severity; bypassing header limits enables resource exhaustion attacks.
- Action
- Update Cowboy to version with duplicate header name validation.
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-2026-65624
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-2026-656240.38% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 31% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-65624 | coverage & exploitation status | NVD · CVE.org |
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