CVE-2026-38821
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
A heap-based buffer overflow vulnerability exists in openNDS before 11.0.0 that allows an unauthenticated attacker on the captive portal network to crash the openNDS daemon (denial of service) and potentially achieve remote code execution. This is in http_microhttpd.c.
Risk Assessment
The attack can disrupt the openNDS service and, in worst cases, enable remote code execution, posing a serious threat to system integrity.
Recommendation
Update openNDS to version 11.0.0 or later and monitor captive portal network traffic for suspicious activities.
Other vulnerabilities in openNDS
See all- CVE-2026-38822High
In openNDS before 11.0.0, the client_params.sh script, invoked by the openNDS daemon to serve the authenticated client status page, is vulnerable to OS command injection through crafted HTTP GET query parameter keys. An authenticated captive portal user can inject arbitrary shell commands by embedding semicolons in a URL query parameter name.
- CVE-2026-38820High
openNDS before 11.0.0 is susceptible to unauthenticated OS command execution via shell command injection through the fas query parameter on the /opennds_preauth/ endpoint because of libopennds.sh.
- CVE-2026-38819Medium
Multiple memory leaks in openNDS before 11.0.0 allow an unauthenticated attacker on the captive portal network to exhaust all available memory on the device within minutes.
Original NVD description (English source)
A heap-based buffer overflow vulnerability exists in openNDS before 11.0.0 that allows an unauthenticated attacker on the captive portal network to crash the openNDS daemon (denial of service) and potentially achieve remote code execution. This is in http_microhttpd.c.