Out-Of-Bounds Write in administrative interface

unknownCVE-2026-40688

CVSSv3 Score: 6.7 An out-of-bounds write vulnerability [CWE-787] in FortiWeb CGI daemon may allow a remote privileged attacker to execute arbitrary code or command via crafted HTTP requests. Revised on 2026-04-15 00:00:00

CSIRTS triage

vendor: Fortinet product: FortiWeb Memory corruption

What: An out-of-bounds write vulnerability may allow a remote privileged attacker to execute arbitrary code.
Who is affected: Privileged users of the FortiWeb administrative interface.
Urgency: Remediation is necessary due to the potential for arbitrary code execution.
Action: Update to the latest software version.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Fortinet FortiGuard PSIRT (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-04-15
Exploitation: Not in CISA KEV at last sync

Original advisory: https://fortiguard.fortinet.com/psirt/FG-IR-26-127

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.

Moderate exploitation riskCVE-2026-406886.4% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 93% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-40688	coverage & exploitation status	NVD · CVE.org

Recent advisories for Out-Of-Bounds Write in

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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unknownCVE-2026-21057: Improper input validation in Samsung Pass prior to version 5.2.10.3 allows local privileged at…nvd · 2026-07-10
unknownCVE-2026-21049: Out-of-bounds write in libpadm.so library prior to SMR Jul-2026 Release 1 allows local attacke…nvd · 2026-07-10
unknownCVE-2026-21048: Out-of-bounds write in parsing DNG format in libimagecodec.media.quram.so prior to SMR Jul-202…nvd · 2026-07-10
unknownCVE-2026-21045: Out-of-bounds write in parsing TIFF format in libimagecodec.media.quram.so prior to SMR Jul-20…nvd · 2026-07-10