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CVE-2018-6332

22
FAUCET Score

CVE-2018-6332 describes a denial-of-service vulnerability in Facebook's HHVM, specifically within its Proxygen HTTP/2 server. This flaw allows an attacker to send invalid HTTP/2 settings, causing the server to consume excessive resources and potentially become unavailable. Rated Medium (CVSS 5.9), the attack is network-based and requires high attack complexity, but can lead to a complete loss of availability. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 3.21.7CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
3.24.3CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:3.24.3:*:*:*:*:*:*:*
< 3.21.8CPE match
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.9MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.09%
Probability of exploitation in next 30 days
EPSS Percentile
61.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0109 is in the 23rd percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

hhvm.com / blog/2018/03/15/hhvm-3.25.html
Vendor Advisory