CVE-2020-1898 json
The fb_unserialize function did not impose a depth limit for nested deserialization.
published 2021-03-11 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-12724
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.2%
- EPSS 1.2% chance of exploitation in 30 days, percentile 68%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Exploit prediction
1.21% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:N/I:N/A:P |
Affected products
- Facebook HHVM
Classification
- Weakness
-
- CWE-674 Uncontrolled Recursion
References
-
github.com
/facebook/hhvm/commit/1746dfb11fc0048366f34669e74318b8278a684c
patch, third-party-advisory
-
hhvm.com
/blog/2020/06/30/security-update.html
vendor-advisory
Sources
- CVE List CVE-2020-1898
- NVD CVE-2020-1898
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