7.5

CVE-2020-1898: facebook hhvm Uncontrolled Recursion

CVSS: 7.5v3.1HighModified
AliasesUBUNTU-CVE-2020-1898
Published 11-03-2021Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2020-1898 is a high (CVSS 7.5) Uncontrolled Recursion vulnerability in facebook hhvm. EPSS estimates a 1.21% chance of exploitation in the next 30 days, higher than 68% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
1.21%
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

The fb_unserialize function did not impose a depth limit for nested deserialization. That meant a maliciously constructed string could cause deserialization to recurse, leading to stack exhaustion. This issue affected 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

1.21%

Chance of exploitation in the next 30 days

Percentile

68%

Versus all other CVEs

30-day change

0.00 pp

From 1.21% on 20-09-2026

20-09-202620-10-2026
EPSS score
1.21%

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