How severe is CVE-2023-27997?

CVE-2023-27997 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2023-27997?

Affected package information for CVE-2023-27997 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2023-27997?

No fixed release is recorded for CVE-2023-27997 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2023-27997 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2023-27997 if there is no patch (or I can't update yet)?

Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Is CVE-2023-27997 actively exploited in the wild?

Yes. There are 11 known exploit references for CVE-2023-27997, including 7 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2023-27997?

CVE-2023-27997 has an EPSS (Exploit Prediction Scoring System) score of 85.7%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2023-27997 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2023-27997 (Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2023-06-13. CISA required all US federal civilian agencies to remediate this vulnerability by 2023-07-04. The required action was: Apply updates per vendor instructions. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2023-27997?

CVE-2023-27997 is classified as CWE-122 (CWE-122), Out-of-bounds Write (CWE-787). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-27997 published, and has it been updated?

CVE-2023-27997 was published on June 13, 2023 and was last updated on July 31, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

CRITICAL severity

CVE-2023-27997

CRITICAL

CVE-2023-27997 is a critical-severity (CVSS 9.8) CWE-122 vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2023-06-13) and has been used in ransomware campaigns — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published

Jun 13, 2023

Updated

Jul 31, 2026

Affected

2 products

Patched

See advisory

Exploits

11 known

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2023-06-13 — including use in ransomware campaigns. Federal agencies were required to remediate by 2023-07-04.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2023-27997.

EPSS Exploitation Probability

via FIRST.org ↗

85.7%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2023-27997 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Counts from FIRST.org, log-scaled.

Description

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.

Affected Products

2 products · 23 configurations

fortiosfortinet

≥ 6.2.9 && ≤ 6.2.13

11 versions

6.0.106.2.46.2.66.2.76.4.26.4.66.4.86.4.106.4.127.0.57.0.10

Application

fortiproxyfortinet

≥ 7.2.0 && ≤ 7.2.3

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.