HOME VULNERABILITIESCVE-2020-1921

HIGH

CVE-2020-1921

CWE-121Published: March 10, 2021· Updated: Jun 17, 2026

7.5

CVSS v3.1

Official Description

In the crypt function, we attempt to null terminate a buffer using the size of the input salt without validating that the offset is within the 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.

Technical Analysis

CVE-2020-1921 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Affected Vendors & Products

facebook1 product(s)

hhvm

Source: NVD CPE · 6 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca

PATCHhttps://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca

ADVISORYhttps://hhvm.com/blog/2021/02/25/security-update.html

ADVISORYhttps://hhvm.com/blog/2021/02/25/security-update.html

All References (4)

→

https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44caPatch · Third Party Advisory

→

https://hhvm.com/blog/2021/02/25/security-update.htmlVendor Advisory

→

https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44caPatch · Third Party Advisory

→

https://hhvm.com/blog/2021/02/25/security-update.htmlVendor Advisory

Quick Facts

CVE IDCVE-2020-1921

CVSS Score7.5 / 10

SeverityHIGH

WeaknessCWE-121

CISA KEVNo

Affected1 vendor(s)

PublishedMar 10, 2021

Related CVEs (CWE-121)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2020-1921 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.

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