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CVE-2018-6345

31
FAUCET Score

CVE-2018-6345 describes a critical heap overflow vulnerability in the number_format function within all supported versions of HHVM (3.30.1 and 3.27.5 and below). An excessively large second argument to this function can lead to the creation of a string with an invalid length, potentially causing further issues. With a CVSS score of 9.8 (CRITICAL), this vulnerability is remotely exploitable with low attack complexity, allowing for high impact on confidentiality, integrity, and availability. While there is no known active exploitation, public exploit code, or KEV listing, the vulnerability has garnered significant community discussion, indicating potential interest.

Impacted Technologies

VendorProductVersion(s)CPE
<= 3.27.5CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
>= 3.28.0, <= 3.30.1CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
< 3.27.6CPE match
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.75%
Probability of exploitation in next 30 days
EPSS Percentile
75.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0175 is in the 63rd percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / facebook/hhvm/commit/190ffdf6c8b1ec443be202c7d69e63a7e3da25e3
PatchThird Party Advisory
hhvm.com / blog/2019/01/14/hhvm-3.30.2.html
Release NotesVendor Advisory