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CVE-2023-27997UnknownPublished

tlp clear · KRVTZ-NET IDS alerts for 2026-05-20

Affects tlp clearSource CIRCL OSINT Feed

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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 · public exploit available · 85% EPSS : block it and hunt for it in your logs now.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
9.2Critical
How severe the flaw is on the 0–10 CVSS scale.
KEV deadline
 US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
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

  1. Disclosed: evidence found.

    CVE published 13 Jun 2023

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CVSS exploit maturity: proof of concept public

  4. Exploited in the wild: evidence found.

    Listed in CISA KEV the same day as disclosure

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by Fortinet, Inc.

    , 96 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. Added to CISA KEV (opens in a new tab)

    exploitation confirmed · ransomware use known

    , the same day as disclosure

  4. KEV remediation due

    US federal deadline

    , 21 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Description

On 2026-05-20, IDS alerts detected network reconnaissance activity involving two IP addresses. One IP made inbound informational requests to a hidden environment file. Another IP repeatedly accessed the Fortigate VPN /remote/logincheck endpoint, linked to CVE-2023-27997, a heap-based buffer overflow vulnerability. No confirmed exploitation or compromise was observed. The activity is classified as reconnaissance with low severity. There are known exploits and ransomware campaigns associated with this vulnerability, but no direct exploitation was confirmed in these alerts.

Indicators of compromise

IP addresses 2

  • 5.255.102.136ET INFO Request to Hidden Environment File - Inbound
  • 2001:470:1:fb5::1a0ET EXPLOIT Fortigate VPN - Repeated GET Requests to /remote/logincheck (CVE-2023-27997)

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