What is CVE-2018-19791?

CVE-2018-19791 is a medium-severity vulnerability in Litespeedtech Openlitespeed, classified under Improper Input Validation. CVSS score: 6.5/10. Published 2018-12-03.

How severe is CVE-2018-19791?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Improper input validation in Litespeedtech Openlitespeed

CVE-2018-19791

The server in LiteSpeed OpenLiteSpeed before 1.5.0 RC6 does not correctly handle requests for byte sequences, allowing an attacker to amplify the response size by requesting the entire response body repeatedly, as demonstrated by an HTTP Range header value beginning with the "bytes=0-,0-" substring.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2018-12-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.012 (68.0th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 68.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Litespeedtech Openlitespeed — versions 1.5.0

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

github.com/litespeedtech/openlitespeed/issues/117 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2018-19791?: CVE-2018-19791 is a medium-severity vulnerability in Litespeedtech Openlitespeed, classified under Improper Input Validation. CVSS score: 6.5/10. Published 2018-12-03.
How severe is CVE-2018-19791?: Medium severity. CVSS v3 base score is 6.5 out of 10.