CVE-2018-6340 — The Memcache::getextendedstats function can be used to trigger an out-of-bounds read

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HIGH

The Memcache::getextendedstats function can be used to trigger an out-of-bounds read

Published Dec 31, 2018

8.1

HIGH

CVSS 3.1

EPSS 1.43%

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).

Affected products

Vendor Facebook Product HHVM Default
n/a
- Version
  3.27.5
  Status
  affected
  Constraints
  -
- Version
  3.30.0
  Status
  affected
  Constraints
  <unspecified
- Version
  3.30.1
  Status
  affected
  Constraints
  -
- Version
  unspecified
  Status
  affected
  Constraints
  <3.27.5

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Facebook

HHVM

n/a

Version	Status	Constraints
3.27.5	affected	-
3.30.0	affected	<unspecified
3.30.1	affected	-
unspecified	affected	<3.27.5

Remediation

No remediation recorded yet.

Metrics

1.43% 0.01430

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.01430

Score over time

2021–2026

EPSS v1
EPSS v5
EPSS v2
EPSS v3

Percentile over time

EPSS v1
EPSS v5
EPSS v2
EPSS v3

Table of values (9 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 1, 2026	1.43% (0.01430)	72.07th	v5 (v2026.06.15)
Sep 20, 2026	1.43% (0.01430)	71.85th	v5 (v2026.06.15)
Jul 20, 2024	0.24% (0.00245)	64.95th	v3 (v2023.03.01)
May 23, 2024	0.24% (0.00245)	64.51th	v3 (v2023.03.01)
Mar 7, 2023	0.24% (0.00235)	59.82th	v3 (v2023.03.01)
Mar 6, 2023	0.89% (0.00885)	27.89th	v2 (v2022.01.01)
Feb 4, 2022	0.89% (0.00885)	10.50th	v2 (v2022.01.01)
Feb 3, 2022	0.62% (0.00624)	17.80th	v5 (v2026.06.15)
Apr 14, 2021	0.62% (0.00624)	0.00th	v1

Weaknesses (1)

CWE-125

Out-of-bounds Read

References (2)

https://github.com/facebook/hhvm/commit/4bff3bfbe90d10451e4638c2118d1ad1117bb3e3
x_refsource_MISCPatchThird Party Advisory
https://hhvm.com/blog/2018/12/18/hhvm-3.30.1.html
x_refsource_MISCThird Party Advisory

Link	Providers	Tags
https://github.com/facebook/hhvm/commit/4bff3bfbe90d10451e4638c2118d1ad1117bb3e3		x_refsource_MISCPatchThird Party Advisory
https://hhvm.com/blog/2018/12/18/hhvm-3.30.1.html		x_refsource_MISCThird Party Advisory