openNDS up to 10.x http_microhttpd.c heap-based overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.3$0-$5k0.94

Summaryinfo

A vulnerability was found in openNDS up to 10.x and classified as very critical. Impacted is an unknown function of the file http_microhttpd.c. The manipulation results in heap-based overflow. This vulnerability is identified as CVE-2026-38821. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in openNDS up to 10.x. It has been classified as very critical. Affected is an unknown code of the file http_microhttpd.c. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-38821 since 04/06/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/28/2026).

Upgrading to version 11.0.0 eliminates this vulnerability.

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Productinfo

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.6
VulDB Meta Temp Score: 8.3

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.1
CNA Vector (MITRE): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Heap-based overflow
CWE: CWE-122 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: openNDS 11.0.0

Timelineinfo

04/06/2026 CVE reserved
08/28/2026 +144 days Advisory disclosed
08/28/2026 +0 days VulDB entry created
08/28/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-38821 (🔒)
GCVE (CVE): GCVE-0-2026-38821
GCVE (VulDB): GCVE-100-396456

Entryinfo

Created: 08/28/2026 04:22
Changes: 08/28/2026 04:22 (63)
Complete: 🔍
Cache ID: 216::103

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