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CriticalKEVRansomware

CVE-2023-27997 — Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability

CVE-2023-27997 · FortiProxy · CVSS 9.8 · KEV

In brief

Severity · CVSS
Critical9.8CVSS 3.1, Critical
EPSS
86%
CISA KEV
Known exploited, listed since 13 Jun 2023
CERT-FR
No advisory or alert referenced in the catalog
Vendor
Fortinet
Published · Modified
·
Last verified

Summary

A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.

Weakness: CWE-122, 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.

12 branches with a published fixed release · 2 branches to migrate

Fortinet FortiOS-6K7K

Source: FG-IR-23-097CVE-2023-27997

  1. 7.0
    Affected versions7.0.5, 7.0.10
    First fixed release7.0.12
  2. 6.4
    Affected versions6.4.2, 6.4.6, 6.4.8, 6.4.10
    5 releases listed6.4.2, 6.4.6, 6.4.8, 6.4.10, 6.4.12
    First fixed release6.4.13
  3. 6.2
    Affected versions6.2.9 – 6.2.136.2.6 – 6.2.76.2.4
    First fixed release6.2.15
  4. 6.0
    Affected versions6.0.12 – 6.0.166.0.10
    First fixed release6.0.17

Releases the vendor does not list are not affected.

Fortinet FortiProxy

Source: FG-IR-23-097CVE-2023-27997

  1. 7.2Approaching end of support
    Affected versions7.2.0 – 7.2.3
    First fixed release7.2.4
  2. 7.0End of life
    Affected versions7.0.0 – 7.0.9
    First fixed release7.0.10
  3. 2.0End of life
    Affected versions2.0.0 – 2.0.12
    First fixed release2.0.13
  4. 1.2End of life
    Affected versions1.2.0 – 1.2.13
    First fixed releaseMigration to a fixed release required
  5. 1.1End of life
    Affected versions1.1.0 – 1.1.6
    First fixed releaseMigration to a fixed release required

Releases the vendor does not list are not affected.

Fortinet FortiOS

Source: FG-IR-23-097CVE-2023-27997

  1. 7.4
    Affected versionsNot affected
    First fixed release—
  2. 7.2End of life
    Affected versions7.2.0 – 7.2.4
    First fixed release7.2.5
  3. 7.0End of life
    Affected versions7.0.0 – 7.0.11
    First fixed release7.0.12
  4. 6.4End of life
    Affected versions6.4.0 – 6.4.12
    First fixed release6.4.13
  5. 6.2End of life
    Affected versions6.2.0 – 6.2.13
    First fixed release6.2.14
  6. 6.0End of life
    Affected versions6.0.0 – 6.0.16
    First fixed release6.0.17

Releases the vendor does not list are not affected.

Remediation

Fix available

Vendor fix

  • FortiOS-6K7K 7.07.0.12
  • FortiOS-6K7K 6.46.4.13
  • FortiOS-6K7K 6.26.2.15
  • FortiOS-6K7K 6.06.0.17
  • FortiProxy 7.27.2.4
  • FortiProxy 7.07.0.10
  • FortiProxy 2.02.0.13
  • FortiOS 7.27.2.5
  • FortiOS 7.07.0.12
  • FortiOS 6.46.4.13
  • FortiOS 6.26.2.14
  • FortiOS 6.06.0.17

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

  • FortiProxy 1.2
  • FortiProxy 1.1

Please upgrade to FortiOS-6K7K version 7.0.12 or above Please upgrade to FortiOS-6K7K version 6.4.13 or above Please upgrade to FortiOS-6K7K version 6.2.15 or above Please upgrade to FortiOS-6K7K version 6.0.17 or above Please upgrade to FortiProxy version 7.2.4 or above Please upgrade to FortiProxy version 7.0.10 or

Full text

above Please upgrade to FortiOS version 7.4.0 or above Please upgrade to FortiOS version 7.2.5 or above Please upgrade to FortiOS version 7.0.12 or above Please upgrade to FortiOS version 6.4.13 or above Please upgrade to FortiOS version 6.2.14 or above Please upgrade to FortiOS version 6.0.17 or above

SourceFortinet (CVE record)

SourceFortiGuard FG-IR-23-097

CISA KEV required action

Apply updates per vendor instructions.

CISA due date:

SourceCISA KEV

Last verified 1 Oct 2026 at 09:29 UTC

Known exploitation

Added to CISA KEV on 13 Jun 2023

Federal remediation due date: 4 Jul 2023

Known use in ransomware campaigns

The CISA required action is shown under Remediation.

86% probability of exploitation in the next 30 days (percentile 100%).

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

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

  1. Added to CISA KEV
  2. Published by the source
  3. CISA remediation due date
  4. Source record last modified
  5. EPSS score computed
  6. Last verified by Patcharo

Official sources

References

Fortinet · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS · FortiGuard FG-IR-23-097

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

All FortiProxy vulnerabilitiesAll FortiOS vulnerabilitiesAll Fortinet vulnerabilities