8.1

CVE-2018-6340: facebook hhvm Out-of-bounds Read

CVSS: 8.1v3.1HighModified
AliasesUBUNTU-CVE-2018-6340
Published 31-12-2018Last modified 06-05-2025
Open JSON

Vulnerability summary

CVE-2018-6340 is a high (CVSS 8.1) Out-of-bounds Read vulnerability in facebook hhvm. EPSS estimates a 1.43% chance of exploitation in the next 30 days, higher than 72.6% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.1/10
010
High · v3.1 (CVE.org)
EPSS score
1.43%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 31-12-2018
    PublishedVulnerability first disclosed.
  2. 06-05-2025
    Last modifiedVulnerability information updated.

Description

The Memcache::getextendedstats function can be used to trigger an out-of-bounds read. Exploiting this issue requires control over memcached server hostnames and/or ports. This affects all supported versions of HHVM (3.30 and 3.27.4 and below).

CVSS metrics

6 scores · 3 sources · 3 versions

EPSS trend

Probability

1.43%

Chance of exploitation in the next 30 days

Percentile

73%

Versus all other CVEs

30-day change

0.00 pp

From 1.43% on 20-09-2026

20-09-202620-10-2026
EPSS score
1.43%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Facebook1 product
  • hhvm3.30.1 | ≥ 3.30.0, < unspecified | 3.27.5 | ≥ unspecified, < 3.27.5 | ≤ 3.27.4 | 3.30
Ubuntu1 product
  • hhvmAll versions (No fix recorded)

2 vendors · 2 products

References

4 links