CVE-2023-27997UnknownPublished 31 Jan 2026

tlp clear · KRVTZ-NET IDS alerts for 2026-01-31

Affects tlp clearSource CIRCL OSINT Feed

TLP:CLEAR, disclosure is not limited

Authoritative record:CVE-2023-27997· Critical 9.2

Exploited in the wild · used in ransomware campaigns · KEV due 4 Jul 2023 · 85% EPSS : block it and hunt for it in your logs now.

Data as of 26 Oct 2026, 09:08 UTC

CVSS 3.1 base score

9.2Critical

How severe the flaw is on the 0–10 CVSS scale.

KEV deadline: 4 Jul 2023 US federal agencies must patch by this date; a sensible deadline for everyone else.
Ransomware: Used in ransomware campaigns
EPSS: 85.6% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:X/RC:R

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 13 Jun 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV the same day as disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

CVE ID reserved
by Fortinet, Inc.
9 Mar 202310:09 UTC, 96 days before disclosure
CVE published
on cve.org
13 Jun 202308:41 UTC, t = 0
Added to CISA KEV (opens in a new tab)
exploitation confirmed · ransomware use known
13 Jun 2023, the same day as disclosure
KEV remediation due
US federal deadline
4 Jul 2023, 21 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Apply updates per vendor instructions.

Description

The KRVTZ-NET IDS alerts from January 31, 2026, report network reconnaissance activities targeting Fortigate VPN devices and web infrastructure. These include scanning behaviors exploiting CVE-2023-27997 on the /remote/logincheck endpoint, as well as probes for hidden environment files and git repositories. No active exploitation or known exploits in the wild have been confirmed at this time. The activity is classified as low severity reconnaissance but poses a medium risk if exploitation occurs, potentially leading to unauthorized access, data leakage, or denial of service. European organizations in finance, government, healthcare, and critical infrastructure sectors are particularly at risk. Mitigation involves patching, access restrictions, monitoring, and network segmentation.

Impact

If exploited, CVE-2023-27997 could lead to unauthorized access to Fortigate VPN devices, resulting in potential data leakage, compromise of confidentiality, integrity, and availability of affected systems. The reconnaissance activity itself does not indicate active exploitation but signals increased targeting of vulnerable infrastructure. The sectors most at risk include finance, government, healthcare, and critical infrastructure in Europe.

Defensive guidance

Mitigation should focus on restricting access to the vulnerable endpoints, implementing enhanced network monitoring to detect suspicious scanning activity, and applying network segmentation to limit exposure. Organizations should follow vendor advisories for updates and apply patches promptly once available.

Summary

The KRVTZ-NET IDS alerts describe reconnaissance activity involving multiple IP addresses conducting scans against Fortigate VPN devices, specifically targeting the /remote/logincheck endpoint to exploit CVE-2023-27997. Additional probes seek hidden environment files and git repositories to gather sensitive information. Although no active exploitation is currently reported, the vulnerability CVE-2023-27997 could allow unauthorized access or denial of service if successfully exploited. The alerts highlight a focus on European organizations relying on Fortigate VPN for secure remote access. The vulnerability is listed in the CISA KEV catalog with a known exploitation date of June 13, 2023. The activity is categorized as reconnaissance with low immediate severity but medium potential impact.

CWE-122Heap-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #16
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
Pre-design: Use a language or compiler that performs automatic bounds checking.
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

Indicators of compromise

IP addresses 6

2620:96:e000::11d- i Censys - HTTP User-Agent Scanner
2001:470:2cc:1::27fET EXPLOIT Fortigate VPN - Repeated GET Requests to /remote/logincheck (CVE-2023-27997)
209.87.169.101ET INFO Request to Hidden Environment File - Inbound
185.198.240.233TGI HUNT gitrepo HTTP Probe
158.101.126.35ET HUNTING Suspicious User-Agent Observed (Mozilla/5.0 (Windows NT XX.X Win64 x64) AppleWebKit/XXX.XX)
206.168.34.217- i Censys - HTTP User-Agent Scanner

Community reviews

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Exploitation evidence

Timeline

What to do

Description

AI analysisMachine-generated, updated 25 Oct 2026, 21:15 UTC

WeaknessesCWE-122

Indicators of compromise

IP addresses 6

Community reviews

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