CVE-2026-40688 | Fortinet FortiWeb up to 7.4.11/7.6.6/8.0.3 out-of-bounds write (FG-IR-26-127)

VDB-357651 · CVE-2026-40688 · FG-IR-26-127 FORTINET FORTIWEB UP TO 7.4.11/7.6.6/8.0.3 OUT-OF-BOUNDS WRITE HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 7.1 $0-$5k 1.36+ Summaryinfo A vulnerability was found in Fortinet FortiWeb up to 7.4.11/7.6.6/8.0.3. It has been rated as critical. This affects an unknown function. Performing a manipulation results in out-of-bounds write. This vulnerability is identified as CVE-2026-40688. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised. Detailsinfo A vulnerability classified as critical has been found in Fortinet FortiWeb up to 7.4.11/7.6.6/8.0.3. This affects an unknown function. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is: A out-of-bounds write vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow attacker to execute unauthorized code or commands via It is possible to read the advisory at fortiguard.fortinet.com. This vulnerability is uniquely identified as CVE-2026-40688 since 04/15/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The exploitation needs additional levels of successful authentication. The technical details are unknown and an exploit is not publicly available. Upgrading eliminates this vulnerability. Productinfo Type Firewall Software Vendor Fortinet Name FortiWeb Version 7.4.0 7.4.1 7.4.2 7.4.3 7.4.4 7.4.5 7.4.6 7.4.7 7.4.8 7.4.9 7.4.10 7.4.11 7.6.0 7.6.1 7.6.2 7.6.3 7.6.4 7.6.5 7.6.6 8.0.0 8.0.1 8.0.2 8.0.3 License commercial Website Vendor: https://www.fortinet.com/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 7.2 VulDB Meta Temp Score: 7.1 VulDB Base Score: 7.2 VulDB Temp Score: 6.9 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 7.2 CNA Vector (fortinet): 🔒 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: Out-of-bounds write CWE: CWE-787 / 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: Upgrade Status: 🔍 0-Day Time: 🔒 Timelineinfo 04/15/2026 Advisory disclosed 04/15/2026 +0 days CVE reserved 04/15/2026 +0 days VulDB entry created 04/15/2026 +0 days VulDB entry last update Sourcesinfo Vendor: fortinet.com Advisory: FG-IR-26-127 Status: Confirmed CVE: CVE-2026-40688 (🔒) GCVE (CVE): GCVE-0-2026-40688 GCVE (VulDB): GCVE-100-357651 Entryinfo Created: 04/15/2026 07:18 Changes: 04/15/2026 07:18 (64) Complete: 🔍 Cache ID: 99:3B9:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸