CVE-2026-6643 | ASUSTOR ADM up to 4.3.3.RR42/5.1.2.REO1 VPN Client sscanf stack-based overflow

VDB-358288 · CVE-2026-6643 · EUVD-2026-23786 ASUSTOR ADM UP TO 4.3.3.RR42/5.1.2.REO1 VPN CLIENT SSCANF STACK-BASED OVERFLOW HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 4.7 $0-$5k 3.94 Summaryinfo A vulnerability classified as critical was found in ASUSTOR ADM up to 4.3.3.RR42/5.1.2.REO1. The impacted element is the function sscanf of the component VPN Client. Executing a manipulation can lead to stack-based overflow. This vulnerability appears as CVE-2026-6643. The attack may be performed from remote. There is no available exploit. Detailsinfo A vulnerability was found in ASUSTOR ADM up to 4.3.3.RR42/5.1.2.REO1. It has been declared as critical. This vulnerability affects the function sscanf of the component VPN Client. The manipulation with an unknown input leads to a stack-based overflow vulnerability. The CWE definition for the vulnerability is CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes: A stack-based buffer overflow vulnerability was found in the VPN Clients on the ADM. The issue stems from the use of unbounded sscanf() and passing user-controlled data directly to printf(). Due to the lack of PIE and Stack Canary protections, an authenticated remote attacker can exploit these to execute arbitrary code as the web server user. Affected products and versions include: from ADM 4.1.0 through ADM 4.3.3.RR42 as well as from ADM 5.0.0 through ADM 5.1.2.REO1. The weakness was presented by Yu-Xiang Huang. The advisory is shared for download at asustor.com. This vulnerability was named CVE-2026-6643 since 04/20/2026. The exploitation appears to be easy. The attack can be initiated remotely. Additional levels of successful authentication are necessary for exploitation. 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 04/20/2026). There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product. The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-23786). Productinfo Vendor ASUSTOR Name ADM Version 4.3.3.RR42 5.1.2.REO1 CPE 2.3info 🔒 🔒 CPE 2.2info 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA CVSS-B Score: 🔒 CNA CVSS-BT Score: 🔒 CNA Vector: 🔒 CVSSv3info VulDB Meta Base Score: 4.7 VulDB Meta Temp Score: 4.7 VulDB Base Score: 4.7 VulDB Temp Score: 4.7 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Stack-based overflow CWE: CWE-121 / CWE-119 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: no mitigation known Status: 🔍 0-Day Time: 🔒 Timelineinfo 04/20/2026 Advisory disclosed 04/20/2026 +0 days CVE reserved 04/20/2026 +0 days VulDB entry created 04/20/2026 +0 days VulDB entry last update Sourcesinfo Advisory: asustor.com Researcher: Yu-Xiang Huang Status: Confirmed CVE: CVE-2026-6643 (🔒) GCVE (CVE): GCVE-0-2026-6643 GCVE (VulDB): GCVE-100-358288 EUVD: 🔒 Entryinfo Created: 04/20/2026 09:36 Updated: 04/20/2026 10:56 Changes: 04/20/2026 09:36 (67), 04/20/2026 10:56 (1) Complete: 🔍 Cache ID: 99:D74:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸