CVE-2020-1918

In-memory file operations (ie: using fopen on a data URI) did not properly restrict negative seeking, allowing for the reading of memory prior to the in-memory buffer. This issue affects HHVM versions prior to 4.56.3, all versions between 4.57.0 and 4.80.1, all versions between 4.81.0 and 4.93.1, and versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0.

Published: 2021-03-10 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-1918 is rated Moderate Risk (49.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.33%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-1918

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.37% 0.33% -0.04%
2 2025-11-18 0.29% 0.37% +0.08%
3 2025-03-30 — 0.29% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-1918

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-1918

OS Trackers for CVE-2020-1918

vendor priority summary link
ubuntu medium CVE-2020-1918 medium priority: Ubuntu including 1 source packages (hhvm), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 13, needs-triage 3. https://ubuntu.com/security/CVE-2020-1918

Affected software / configurations for CVE-2020-1918

Vendor Product Version Raw CPE
facebook hhvm < 4.56.3 cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm >= 4.57.0, < 4.80.2 cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm >= 4.81.0, < 4.93.2 cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm 4.94.0 cpe:2.3:a:facebook:hhvm:4.94.0:*:*:*:*:*:*:*
facebook hhvm 4.95.0 cpe:2.3:a:facebook:hhvm:4.95.0:*:*:*:*:*:*:*
facebook hhvm 4.96.0 cpe:2.3:a:facebook:hhvm:4.96.0:*:*:*:*:*:*:*
facebook hhvm 4.97.0 cpe:2.3:a:facebook:hhvm:4.97.0:*:*:*:*:*:*:*
facebook hhvm 4.98.0 cpe:2.3:a:facebook:hhvm:4.98.0:*:*:*:*:*:*:*

References for CVE-2020-1918

cvelogic Threat Intelligence