# CVE-2026-126254: Fortinet FortiOS numeric truncation error in BGP daemon

Source: https://junglewise.ai/threats/cve-2026-126254-a-numeric-truncation-error-vulnerability-in-fortinet-fortios-8-0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-11  
License: CC BY 4.0 with a link back

CVE-2026-126254 · Severity: critical · CVSS 9.6 · Published 2026-11-11

FortiOS is network routing software used by enterprises to manage BGP traffic between routers. A numeric truncation error in the BGP daemon allows a malicious internal BGP neighbor to send crafted attributes that propagate to all connected routers, potentially causing denial of service across the entire routing infrastructure.

Technologies: [Fortinet FortiOS](https://junglewise.ai/threats/technologies/fortios), [Fortinet Fortisase](https://junglewise.ai/threats/technologies/fortisase). Vendors: [Fortinet](https://junglewise.ai/threats/vendors/fortinet).

## Quick answers

**Is CVE-2026-126254 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126254 being exploited in the wild.

**How severe is CVE-2026-126254?** Critical severity, with a CVSS score of 9.6, published 11 November 2026.

**Which products and versions are affected?** Fortinet FortiOS 8.0.0 through 8.0.1, 7.6.0 through 7.6.7, 7.4.0 through 7.4.12, 7.2.0 through 7.2.13; Fortinet Fortisase 25.1 through 26.3.1, 26.2 all versions.

**Is there a fix for CVE-2026-126254?** Yes: fixed in FortiOS 8.0.2 or above, 7.6.8 or above, 7.4.13 or above, 7.2.14 or above; FortiSASE 26.3.2 or above (26.3.1 and earlier affected; 26.2 and earlier require migration to fixed release). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126254 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-126254?** Check whether you run Fortinet FortiOS or Fortinet Fortisase at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in FortiOS 8.0.2 or above, 7.6.8 or above, 7.4.13 or above, 7.2.14 or above; FortiSASE 26.3.2 or above (26.3.1 and earlier affected; 26.2 and earlier require migration to fixed release)

## Technical details

A numeric truncation error (CWE-197) in the FortiOS and FortiSASE BGP daemon allows a configured iBGP neighbor to send specially crafted malformed attributes that propagate to all connected routers. The vulnerability requires authentication as a configured BGP neighbor and operates over the network. Exploitation causes denial of service impact.

## Affected products

- Fortinet FortiOS 8.0.0 through 8.0.1, 7.6.0 through 7.6.7, 7.4.0 through 7.4.12, 7.2.0 through 7.2.13
- Fortinet FortiSASE 25.1 through 26.3.1, 26.2 all versions

## Timeline

- 2026-11-10: disclosed

## References

- [https://fortiguard.fortinet.com/psirt/FG-IR-26-268](https://fortiguard.fortinet.com/psirt/FG-IR-26-268)

## Related threats

- [Fortinet FortiOS authentication bypass in HA command execution](https://junglewise.ai/threats/cve-2026-126259-a-missing-authentication-for-critical-function-vulnerability-in)
- [Fortinet FortiOS stack buffer overflow in WAD proxy](https://junglewise.ai/threats/cve-2026-126258-a-stack-based-buffer-overflow-vulnerability-in-fortinet-fortios)
- [Fortinet FortiOS out-of-bounds read in kernel](https://junglewise.ai/threats/cve-2026-126256-a-out-of-bounds-read-vulnerability-in-fortinet-fortios-8-0-0)
- [Fortinet FortiOS path traversal authentication bypass in SSH daemon](https://junglewise.ai/threats/cve-2026-126255-a-path-traversal-filedir-vulnerability-in-fortinet-fortios-8-0-0)
- [Fortinet FortiOS authentication bypass in OSPF daemon](https://junglewise.ai/threats/cve-2026-126253-a-authentication-bypass-by-primary-weakness-vulnerability-in)