6.5

CVE-2018-13383: Fortinet FortiOS and FortiProxy Out-of-bounds Write

CVSS: 6.5v3.1MediumKEVRansomwareAnalyzed
Published 29-05-2019Last modified 21-10-2025
Open JSON

Vulnerability summary

CVE-2018-13383 is a medium (CVSS 6.5) Out-of-bounds Write vulnerability in Fortinet FortiOS and FortiProxy. It is known to be exploited: CISA lists it, first on 10-01-2022. It has been used in ransomware campaigns. EPSS estimates a 33.65% chance of exploitation in the next 30 days, higher than 98.3% of scored vulnerabilities.

Overall risk
90/100
0100
Critical · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (NVD)
EPSS score
33.65%
0%100%
High · 0.00 pp in 30 days
KEVListedCISA
RansomwareKnown useFlagged by CISA
Public exploits0No public exploits recorded

Timeline

  1. 29-05-2019
    PublishedVulnerability first disclosed.
  2. 10-01-2022
    Added to CISA KEVFortinet FortiOS and FortiProxy Out-of-bounds Write
  3. 10-07-2022
    CISA remediation dueApply updates per vendor instructions.
  4. 21-10-2025
    Last modifiedVulnerability information updated.

Description

A heap buffer overflow in Fortinet FortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.10, 5.4.0 through 5.4.12, 5.2.14 and earlier and FortiProxy 2.0.0, 1.2.8 and earlier in the SSL VPN web portal may cause the SSL VPN web service termination for logged in users due to a failure to properly handle javascript href data when proxying webpages.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

33.65%

Chance of exploitation in the next 30 days

Percentile

98%

Versus all other CVEs

30-day change

0.00 pp

From 33.65% on 19-09-2026

19-09-202619-10-2026
EPSS score
33.65%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
10-01-2022
Federal due date
10-07-2022
Ransomware

CISA required action

Apply updates per vendor instructions. nvd.nist.gov/vuln/detail/CVE-2018-13383

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Fortinet3 products
  • fortinet fortios and fortiproxyFortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.10, 5.4.0 through 5.4.12, 5.2.14 and earlier, FortiProxy 2.0.0, 1.2.8 and earlier
  • fortios≥ 5.2.0, < 5.2.15 | ≥ 5.4.0, < 5.4.13 | ≥ 5.6.0, < 5.6.11 | ≥ 6.0.0, < 6.0.5
  • fortiproxy< 1.2.9 | 2.0.0

1 vendor · 3 products

References

3 links