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CVE-2025-53844 — A out-of-bounds write vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, For…

CVE-2025-53844 · FortiOS · CVSS 8.8

In brief

Severity · CVSS
High8.8CVSS 3.1, High
EPSS
0.56%
CISA KEV
Not listed
Vendor
Fortinet
Products
FortiOS
Published · Modified
·
Last verified

Summary

A out-of-bounds write vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2.0 through 7.2.11 allows attacker to execute unauthorized code or commands via specially crafted packets.

Weakness: CWE-787

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

4 branches with a published fixed release · 1 branch to migrate

Fortinet FortiOS

Source: FG-IR-26-123CVE-2025-53844

  1. 8.0
    Affected versionsNot affected
    First fixed release—
  2. 7.6
    Affected versions7.6.0 – 7.6.3
    First fixed release7.6.4
  3. 7.4
    Affected versions7.4.0 – 7.4.8
    First fixed release7.4.9
  4. 7.2End of life
    Affected versions7.2.0 – 7.2.11
    First fixed release7.2.12
  5. 7.0End of life
    Affected versions7.0.0 – 7.0.17
    First fixed release7.0.18
  6. 6.4End of life
    Affected versions6.4.0 – 6.4.16
    First fixed release6.4.17 (upcoming)
  7. 6.2End of life
    Affected versions6.2.0 – 6.2.17
    First fixed release6.2.18 (upcoming)
  8. 6.0End of life
    Affected versions6.0.0 – 6.0.18
    First fixed releaseMigration to a fixed release required

Releases the vendor does not list are not affected.

Remediation

Fix available

Vendor fix

  • FortiOS 7.67.6.4
  • FortiOS 7.47.4.9
  • FortiOS 7.27.2.12
  • FortiOS 7.07.0.18

Upgrade to a fixed release listed above for your branch, or to a later fixed release the vendor explicitly supports.

Branches without a fix of their own: migrate to a fixed release

  • FortiOS 6.0

Upgrade to FortiOS version 7.6.4 or above Upgrade to FortiOS version 7.4.9 or above Upgrade to FortiOS version 7.2.12 or above Upgrade to FortiOS version 7.0.18 or above Fortinet remediated this issue in FortiSASE version 25.3.a and hence customers do not need to perform any action.

Full text

Upgrade to FortiSwitchManager version 7.2.7 or above Upgrade to FortiSwitchManager version 7.0.6 or above Fortinet remediated this issue in FortiEdgeCloud version 25.3 and hence customers do not need to perform any action.

SourceFortinet (CVE record)

SourceFortiGuard FG-IR-26-123

CERT-FR recommendation

Refer to the vendor's security bulletin to obtain patches (see Documentation section).

SourceCERTFR-2026-AVI-0575

Last verified 1 Oct 2026 at 09:29 UTC

Known exploitation

Not listed in CISA KEV as of the last check.

0.56% probability of exploitation in the next 30 days (percentile 45%).

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CERT-FR

1 document of the French national CERT (ANSSI) references this CVE.

Advisory (AVI)CERTFR-2026-AVI-0575Published 13 May 2026

Multiple vulnerabilities in Fortinet products

Remote arbitrary code executionPrivilege escalationRemote denial of serviceData confidentiality breachData integrity breachSecurity policy bypassNot specified by the vendorSQL injection (SQLi)

Summary

Multiple vulnerabilities have been discovered in Fortinet products. Some of them allow an attacker to cause remote arbitrary code execution, privilege escalation, and remote denial of service.

Recommendation

Refer to the vendor's security bulletin to obtain patches (see Documentation section).

Official document on cert.ssi.gouv.frread by Patcharo 28 Sept 2026 at 20:03 UTCMachine translation of the French text published by CERT-FR; a text whose translation did not pass Patcharo's checks stays in French. Identifiers, versions and links are copied unchanged.

Timeline

  1. Published by the source
  2. EPSS score computed
  3. Source record last modified
  4. Last verified by Patcharo

Official sources

References

Fortinet · NVD · FIRST EPSS · FortiGuard FG-IR-26-123

How Patcharo reads this

Affected and fixed releases come from the vendor's structured statements and are matched against exact versions; CVSS from NVD, exploitation from CISA KEV and the vendor's own advisory, probability from FIRST EPSS. Missing data stays Unknown and never becomes Not affected.

Read the methodologyRead the guide: FortiOS version numbering: branches, patch releases and the Feature and Mature labels

Related vulnerabilities

Other records affecting the same products, newest first.

  • CVE-2026-71407A Stack-based Buffer Overflow vulnerability [CWE-121] vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6 m…High
  • CVE-2025-53847A missing authentication for critical function vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS…High
  • CVE-2025-68686Fortinet FortiOS Exposure of Sensitive Information to an Unauthorized Actor VulnerabilityMediumKEV
  • CVE-2025-64157A use of externally-controlled format string vulnerability in Fortinet FortiOS 7.6.0 through 7.6.4, FortiOS 7…High
  • CVE-2026-22153An Authentication Bypass by Primary Weakness vulnerability [CWE-305] vulnerability in Fortinet FortiOS 7.6.0 …High

All FortiOS vulnerabilitiesAll Fortinet vulnerabilities