🛡️ CVE-2026-39811 — fortiweb

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

• Attack vector: Network — reachable from anywhere that can route to the service.
• Attack complexity: Low — the attack works reliably, with no preparation.
• Privileges required: High — administrative rights are needed first.
• User interaction: None — nobody has to be tricked into anything.
• Scope: Unchanged — the damage stays inside the vulnerable component.
• Confidentiality impact: None.
• Integrity impact: None.
• Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-39811 is classified as CWE-190: Integer Overflow or Wraparound. Arithmetic produces a value too large for its type and wraps around, so a later size or bounds check passes when it should not.

Affected software

CVE-2026-39811 is recorded against 1 package.

• fortiweb (from 8.0.0 up to 8.0.4)

Timeline and source

Published on 14 April 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

fortiguard.fortinet.com

Other advisories for this package

fortiweb has other advisories on record. If you are patching this one, these are worth checking on the same host:

• CVE-2026-40688 (7.2 High, published 14 Apr 2026)
• CVE-2026-39814 (6.7 Medium, published 14 Apr 2026)
• CVE-2026-24640 (6.6 Medium, published 10 Mar 2026)
• CVE-2026-24017 (8.1 High, published 10 Mar 2026)
• CVE-2025-66178 (7.2 High, published 10 Mar 2026)
• CVE-2026-30897 (6.6 Medium, published 10 Mar 2026)
• CVE-2025-48840 (5.3 Medium, published 10 Mar 2026)
• CVE-2026-24641 (2.7 Low, published 10 Mar 2026)

Same weakness in other software

These advisories are the same class of weakness (CWE-190: Integer Overflow or Wraparound) in other software:

• CVE-2022-36015 (8.0 High, published 13 Jul 2026)
• CVE-2023-25667 (8.0 High, published 13 Jul 2026)
• CVE-2023-25662 (8.0 High, published 13 Jul 2026)
• CVE-2017-12864 (8.0 High, published 9 Jul 2026)
• CVE-2017-12863 (8.0 High, published 9 Jul 2026)
• CVE-2022-23575 (8.0 High, published 9 Jul 2026)
• CVE-2022-23567 (8.0 High, published 9 Jul 2026)
• CVE-2017-1000450 (8.0 High, published 2 Jul 2026)

Details

Affected Packages

References