How severe is CVE-2018-19791?

CVE-2018-19791 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-19791 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-19791?

CVE-2018-19791 primarily affects Litespeedtech Openlitespeed. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-19791?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-19791 published?

CVE-2018-19791 was published on 2018-12-03 and last updated on 2026-06-17.

CVE-2018-19791

CVE-2018-19791 is a medium-severity vulnerability in Litespeedtech Openlitespeed with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Litespeedtech Openlitespeed
Published: 2018-12-03
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2018-19791?: CVE-2018-19791 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-19791 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-19791?: CVE-2018-19791 primarily affects Litespeedtech Openlitespeed. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-19791?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-19791 published?: CVE-2018-19791 was published on 2018-12-03 and last updated on 2026-06-17.

References

https://github.com/litespeedtech/openlitespeed/issues/117

Affected products (7)

cpe:2.3:a:litespeedtech:openlitespeed:*:*:*:*:*:*:*:*
cpe:2.3:a:litespeedtech:openlitespeed:1.5.0:-:*:*:*:*:*:*
cpe:2.3:a:litespeedtech:openlitespeed:1.5.0:rc1:*:*:*:*:*:*
cpe:2.3:a:litespeedtech:openlitespeed:1.5.0:rc2:*:*:*:*:*:*
cpe:2.3:a:litespeedtech:openlitespeed:1.5.0:rc3:*:*:*:*:*:*
cpe:2.3:a:litespeedtech:openlitespeed:1.5.0:rc4:*:*:*:*:*:*
cpe:2.3:a:litespeedtech:openlitespeed:1.5.0:rc5:*:*:*:*:*:*

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