Heap overflow in kernel driver due to missing size validation

unknownCVE-2026-70465

CVSSv3 Score: 7.3 A buffer copy without checking size of input vulnerability [CWE-120] in FortiClient Windows may allow an unauthenticated attacker in a position to alter or craft DNS responses to the targeted host to execute arbitrary code via malicious packets. Revised on 2026-08-12 00:00:00

CSIRTS triage

vendor: Fortinet product: FortiClient Memory corruption Remote code execution

What: Buffer overflow vulnerability in FortiClient Windows kernel driver allows arbitrary code execution via crafted DNS responses.
Who is affected: Windows systems running FortiClient that can be targeted with malicious DNS responses.
Urgency: High urgency; CVSS 7.3 enables code execution without user interaction via network-level attacks.
Action: Update FortiClient Windows to patch CVE-2026-70465 and consider network-level DNS security controls.

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: 2026-08-12
Exploitation: Not in CISA KEV at last sync

Original advisory: https://fortiguard.fortinet.com/psirt/FG-IR-26-156

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.

Low exploitation riskCVE-2026-704650.55% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 43% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-70465	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownNCSC-2026-0296 [1.00] [M/H] Vulnerability patched in Fortinet FortiClientncsc-nl
high[NEW] [high] Fortinet FortiClient: Vulnerability enables code executioncert-bund
unknownFortinet Products Multiple Vulnerabilitieshkcert
unknownMultiple vulnerabilities in Fortinet products (August 13, 2026)cert-fr-avis
highCVE-2026-70465: A buffer copy without checking size of input ('classic buffer overflow') vulnerability in Fort…nvd

Recent advisories for Heap overflow 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.

highCVE-2026-74378: In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix TOCTOU heap …nvd · 2026-08-15
highCVE-2026-74341: In the Linux kernel, the following vulnerability has been resolved: wifi: wcn36xx: fix heap ov…nvd · 2026-08-15
highCVE-2026-72262: In the Linux kernel, the following vulnerability has been resolved: ASoC: SOF: ipc3-control: F…nvd · 2026-08-15
highCVE-2026-72003: In the Linux kernel, the following vulnerability has been resolved: wifi: brcmfmac: cyw: fix h…nvd · 2026-08-15
highCVE-2026-72970: Heap-based buffer overflow in Microsoft Edge (Chromium-based) allows an unauthorized attacker …nvd · 2026-08-14
highCVE-2026-16982: IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service due to…nvd · 2026-08-13