No exploitation reportedFix available

CVE-2018-8777

Q: Is CVE-2018-8777 actively exploited?

Active exploitation of CVE-2018-8777 has not been confirmed. Its EPSS score was 4.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2018-8777?

CVE-2018-8777 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2018-04-03
WeaknessCWE-400

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, an attacker can pass a large HTTP request with a crafted header to WEBrick server or a crafted body to WEBrick server/handler and cause a denial of service (memory consumption).

Timeline

dates in UTC

2018-04-0322:29CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2018-8777?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2018-8777?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Redhat enterprise linux

Branch	Affected	Fixed in	Source
6.0	= 6.0	no fix published	NVD
7.0	= 7.0	no fix published	NVD
7.4	= 7.4	no fix published	NVD
7.5	= 7.5	no fix published	NVD
7.6	= 7.6	no fix published	NVD

Ruby

Branch	Affected	Fixed in	Source
2.5	≥ 2.5.0, < 2.5.1	2.5.1	NVD
2.4	≥ 2.4.0, < 2.4.4	2.4.4	NVD
2.3	≥ 2.3.0, < 2.3.7	2.3.7	NVD
2.2	≥ 2.2.0, < 2.2.10	2.2.10	NVD
2.6	= 2.6.0	no fix published	NVD

Canonical ubuntu linux

Branch	Affected	Fixed in	Source
14.4	= 14.04	no fix published	NVD
16.4	= 16.04	no fix published	NVD
17.10	= 17.10	no fix published	NVD

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

www.ruby-lang.orgVendor Advisory
www.ruby-lang.orgPatch · Vendor Advisory
www.ruby-lang.orgPatch · Vendor Advisory
www.ruby-lang.orgPatch · Vendor Advisory
www.ruby-lang.orgPatch · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.07.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
NVDweakness (CWE)CWE-400read 2026-10-23
FIRST EPSSEPSS score4.5 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2018-04-03
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2018-8777?

Is CVE-2018-8777 actively exploited?

Active exploitation of CVE-2018-8777 has not been confirmed. Its EPSS score was 4.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-8777?

CVE-2018-8777 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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