CVE-2023-27997UnknownPublished 5 Feb 2026

tlp clear · KRVTZ-NET IDS alerts for 2026-02-05

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, 07:57 UTC

CVSS 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.

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
2023-03-0910:09Z, 96 days before disclosure
CVE published
on cve.org
2023-06-1308:41Z, t = 0
Added to CISA KEV (opens in a new tab)
exploitation confirmed · ransomware use known
2023-06-13, the same day as disclosure
KEV remediation due
US federal deadline
2023-07-04, 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 2026-10-26.

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 February 5, 2026, report reconnaissance activities targeting Fortigate VPN devices and web applications vulnerable to JavaScript prototype pollution. The reconnaissance includes scanning and probing from multiple IP addresses, with repeated attempts to exploit CVE-2023-27997, which allows unauthenticated attackers to bypass authentication on Fortigate VPNs. No active exploitation or lateral movement has been observed. The overall severity of this reconnaissance phase is low, but it indicates ongoing threat actor interest. Organizations, particularly in Europe, using Fortigate VPNs or vulnerable web applications should prioritize patching and hardening to mitigate future risks.

Impact

The reconnaissance activity targets Fortigate VPN devices vulnerable to CVE-2023-27997, which allows unauthenticated attackers to bypass authentication. While no active exploitation or lateral movement has been observed, successful exploitation could lead to unauthorized access to VPN infrastructure. Additionally, attempts to exploit JavaScript prototype pollution vulnerabilities in web applications could lead to client-side attacks if successful. The current impact is limited to reconnaissance with no confirmed exploitation, but the presence of known exploits in the wild and known ransomware campaign use increases potential risk.

Defensive guidance

Organizations should prioritize monitoring for suspicious scanning and exploitation attempts targeting Fortigate VPNs and vulnerable web applications. Hardening VPN configurations and web application security controls is recommended. Since no active exploitation has been observed, immediate emergency response is not required, but proactive defense measures should be implemented. Stay updated with vendor advisories for any forthcoming patches or mitigations.

Summary

On 2026-02-05, KRVTZ-NET IDS detected reconnaissance activities focusing on network infrastructure, specifically Fortigate VPN devices and web applications susceptible to JavaScript prototype pollution. Multiple IPs performed scanning and probing, including repeated GET requests exploiting CVE-2023-27997, an authentication bypass vulnerability in Fortigate VPNs. Additional scanning involved HTTP User-Agent fingerprinting and attempts to exploit prototype pollution via the __proto__ property in HTTP bodies. No active exploitation or lateral movement was observed. There are no patches currently available, but the vulnerability is known and listed in the CISA KEV catalog since June 2023. The reconnaissance is assessed as low severity but highlights threat actor interest in these vectors.

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 4

162.142.125.39- i Censys - HTTP User-Agent Scanner
2001:470:1:332::7ET EXPLOIT Fortigate VPN - Repeated GET Requests to /remote/logincheck (CVE-2023-27997)
34.83.176.217ET HUNTING Javascript Prototype Pollution Attempt via __proto__ in HTTP Body
2620:96:e000::104- i Censys - HTTP User-Agent Scanner

Community reviews

Loading reviews…

Exploitation evidence

Timeline

What to do

Description

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

WeaknessesCWE-122

Indicators of compromise

IP addresses 4

Community reviews

Related threats