FortiproxyApplication · Fortinet

CVE-2023-27997

CRITICAL · 9.8 CVSS v3.1 Published 2023-06-13

Fix available

A fix is available. Upgrade to after 7.2.4 or later.

See remediation →

100/100

Remediation priority · Urgent

In the wild Ransomware High EPSS Remotely reachable No privileges Zero-click

Official description

NVD · unedited

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.

Technical summary

dbcve analysis · high confidence

Heap-based buffer overflow in FortiOS and FortiProxy SSL-VPN allows remote attackers to execute arbitrary code via specially crafted requests. The vulnerability stems from improper bounds checking in the SSL-VPN component, enabling an attacker to overflow heap memory and gain code execution privileges.

MitigationUpgrade FortiOS to version 7.2.5+, 7.0.12+, 6.4.13+, or 6.0.17+ and FortiProxy to version 7.2.4+, 7.0.10+, or 2.0.13+ based on the affected branch. If immediate patching is not possible, disable SSL-VPN or restrict access to trusted IP ranges as a temporary workaround.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

FortiproxyApplication

Affected:>= 1.1.0, <= 1.1.6>= 1.2.0, <= 1.2.13>= 2.0.0, <= 2.0.12>= 7.0.0, <= 7.0.9>= 7.2.0, <= 7.2.3

FortiosOperating system

Affected:>= 6.0.0, <= 6.0.16>= 6.2.0, <= 6.2.13>= 6.4.0, <= 6.4.12>= 7.0.0, <= 7.0.11>= 7.2.0, <= 7.2.4>= 6.0.12, <= 6.0.16>= 6.2.9, <= 6.2.13= 6.0.10= 6.2.4= 6.2.6= 6.2.7= 6.4.2

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify the product and firmware version

Run 'get system status' via CLI or check the FortiOS/FortiProxy web UI dashboard for firmware version

Affected if The version matches any of the following ranges: FortiOS 6.0.0-6.0.16, 6.2.0-6.2.13, 6.4.0-6.4.12, 7.0.0-7.0.11, 7.2.0-7.2.4 (including specific versions 6.0.10, 6.2.4, 6.2.6, 6.2.7, 6.4.2); FortiProxy 1.1.0-1.1.6, 1.2.0-1.2.13, 2.0.0-2.0.12, 7.0.0-7.0.9, 7.2.0-7.2.3
Confirm SSL-VPN is enabled

Run 'get vpn ssl settings' via CLI or check SSL-VPN configuration in web UI under VPN > SSL-VPN Settings

Affected if SSL-VPN is enabled and listening on the external interface (ssl.vpn.ip or ssl.dtp.tcp port is configured)
Check SSL-VPN access policy restrictions

Run 'get firewall policy' and filter for 'ssl.root' as source interface, or check VPN > SSL-VPN > SSL-VPN Policies in web UI

Affected if There is an SSL-VPN policy allowing access from 'all' or untrusted IP ranges (0.0.0.0/0) without IP restriction

You are affected if your FortiOS or FortiProxy version falls within the affected ranges AND SSL-VPN is enabled and accessible from untrusted networks.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to a release after 7.2.4

Interim mitigation

Upgrade FortiOS to version 7.2.5+, 7.0.12+, 6.4.13+, or 6.0.17+ and FortiProxy to version 7.2.4+, 7.0.10+, or 2.0.13+ based on the affected branch. If immediate patching is not possible, disable SSL-VPN or restrict access to trusted IP ranges as a temporary workaround.

Recommended fix High confidence

FortiOS: 6.0.17+, 6.4.13+, 7.0.12+, 7.2.5+ | FortiProxy: 2.0.13+, 7.0.10+, 7.2.4+

1. Identify the exact FortiOS or FortiProxy version currently installed by running 'get system status' or 'fnsysctl get system status' via CLI
2. Based on your current version, upgrade to the fixed version: For FortiOS 6.0.x, upgrade to 6.0.17 or later; For FortiOS 6.4.x, upgrade to 6.4.13 or later; For FortiOS 7.0.x, upgrade to 7.0.12 or later; For FortiOS 7.2.x, upgrade to 7.2.5 or later; For FortiProxy 1.1.x and 1.2.x, upgrade to 2.0.13 or later; For FortiProxy 7.0.x, upgrade to 7.0.10 or later; For FortiProxy 7.2.x, upgrade to 7.2.4
3. Download the firmware upgrade from Fortinet's support portal (support.fortinet.com)
4. Upload and install the firmware via the FortiOS/FortiProxy GUI or CLI using 'execute firmware upgrade' command
5. After upgrade, verify the new version is installed with 'get system status' and confirm the vulnerability is resolved
6. If immediate upgrade is not possible, disable SSL-VPN (go to VPN > SSL-VPN Settings and disable 'Enable SSL-VPN') as a temporary mitigation

Caveat Review Fortinet release notes for each version for potential configuration or feature changes before upgrading; some upgrades may require reboots and cause brief downtime

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fortiproxy Exploited in the wild — priority engagement

Consultation4.0 h
Implementation2.0 h
Testing2.0 h
Review / QA2.0 h

10.0 hours of engineering $1,820

Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,912.

Scan for this in your stack

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References

Primary sources

fortiguard.comVendor Advisory
www.cisa.govUS Government Resource
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-27997 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2023-27997?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

Exploited in the wildOn CISA’s known-exploited list · agencies must fix by 2023-07-04

A fix existsUpgrade to after 7.2.4 or later

Severity 9.8 Critical

Exploit likelihood EPSS, next 30 days 85.7%

Affects: Fortiproxy

Remediation

Being exploited — close it fast

Fix this in Fortiproxy 10 hrs · Low

Typical engagement from $1,820

Get it fixed fast See the full breakdown ↓

This CVE is on CISA’s actively-exploited list, so the clock is real — a vetted specialist can deliver a reviewed fix for your staging environment quickly.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References