CVE-2024-21762Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via chunked trailer overwrite

Published Feb 9, 2024 · Updated Aug 4, 2026

Out-of-bounds write in Fortinet FortiOS and FortiProxy allows remote attackers to execute code through crafted SSL-VPN requests. The sslvpnd HTTP parser accepts an oversized chunk-size field and writes trailer delimiters past the request buffer after a zero-length chunk. No authentication or user interaction is required when SSL VPN is enabled, and successful corruption redirects control flow to attacker-supplied code.

CVSS severity9.8
Critical
EPSS probability84.28%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Fortinet FortiOS and FortiProxy allows remote attackers to execute code through crafted SSL-VPN requests. The sslvpnd HTTP parser accepts an oversized chunk-size field and writes trailer delimiters past the request buffer after a zero-length chunk. No authentication or user interaction is required when SSL VPN is enabled, and successful corruption redirects control flow to attacker-supplied code.

The record

CVE
CVE-2024-21762
Published
Feb 9, 2024
Updated
Aug 4, 2026
Vendor
Fortinet
Product
FortiOS
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2024Exploitation reportedCISA Known Exploited Vulnerabilities Catalog entry
  2. Feb 9, 2024CVE publishedPublication date reported by the CVE source.
  3. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.0.0 <=6.0.17
  2. Affected versionversion=6.0.0 <6.2.16
  3. Affected versionversion=6.2.0 <=6.2.15
  4. Affected versionversion=6.4.0 <=6.4.14
  5. Affected versionversion=6.4.0 <6.4.15
  6. Affected versionversion=7.0.0 <=7.0.13
  7. Affected versionversion=7.0.0 <7.0.14
  8. Affected versionversion=7.2.0 <=7.2.6
  9. Affected versionversion=7.2.0 <7.2.7
  10. Affected versionversion=7.4.0 <=7.4.2
  11. Affected versionversion=7.4.0 <7.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fortinet · FortiOSversion=6.0.0 <=6.0.17; version=6.0.0 <6.2.16; version=6.2.0 <=6.2.15; version=6.4.0 <=6.4.14; version=6.4.0 <6.4.15; version=7.0.0 <=7.0.13; version=7.0.0 <7.0.14; version=7.2.0 <=7.2.6; version=7.2.0 <7.2.7; version=7.4.0 <=7.4.2; version=7.4.0 <7.4.3
Fortinet · FortiProxyversion=1.0.0 <=1.0.7; version=1.0.0 <2.0.14; version=1.1.0 <=1.1.6; version=1.2.0 <=1.2.13; version=2.0.0 <=2.0.13; version=7.0.0 <=7.0.14; version=7.0.0 <7.0.15; version=7.2.0 <=7.2.8; version=7.2.0 <7.2.9; version=7.4.0 <=7.4.2; version=7.4.0 <7.4.3

Published CVSS scores

9.6FortinetCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:W/RC:C
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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