9.8

CVE-2020-1900: facebook hhvm Use After Free

CVSS: 9.8v3.1CriticalModified
AliasesUBUNTU-CVE-2020-1900
Published 11-03-2021Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2020-1900 is a critical (CVSS 9.8) Use After Free vulnerability in facebook hhvm. EPSS estimates a 1.38% chance of exploitation in the next 30 days, higher than 71.8% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (NVD)
EPSS score
1.38%
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. 11-03-2021
    PublishedVulnerability first disclosed.
  2. 04-08-2024
    Last modifiedVulnerability information updated.

Description

When unserializing an object with dynamic properties HHVM needs to pre-reserve the full size of the dynamic property array before inserting anything into it. Otherwise the array might resize, invalidating previously stored references. This pre-reservation was not occurring in HHVM prior to v4.32.3, between versions 4.33.0 and 4.56.0, 4.57.0, 4.58.0, 4.58.1, 4.59.0, 4.60.0, 4.61.0, 4.62.0.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

1.38%

Chance of exploitation in the next 30 days

Percentile

72%

Versus all other CVEs

30-day change

0.00 pp

From 1.38% on 20-09-2026

20-09-202620-10-2026
EPSS score
1.38%

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
  • hhvm≥ 4.58.0, < unspecified | ≥ 4.33.0, < unspecified | ≥ unspecified, < 4.32.3 | < 4.32.3 | ≥ 4.33.0, < 4.56.1 | 4.57.0 | 4.58.0 | 4.58.1 | 4.59.0 | 4.60.0 | 4.61.0 | 4.62.0
Ubuntu1 product
  • hhvmAll versions (No fix recorded)

2 vendors · 2 products

References

4 links