CVE-2026-43966: HTTP Response Splitting via Non-VCHAR Bytes in cow_http_struct_hd:escape_string/2
CSIRTS triage
- What
- HTTP response splitting can occur via non-VCHAR bytes in the cow_http_struct_hd escape_string function.
- Who is affected
- Deployments using the affected HTTP handling functionality.
- Urgency
- Remediation urgency is unknown due to lack of severity information.
- Action
- Monitor for updates and apply patches when available.
AI-assisted analysis generated from the source advisory — verify against the original.
Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-43966
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-2026-439660.31% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 23% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-43966 | coverage & exploitation status | NVD · CVE.org |
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