CVE-2020-1900 json
When unserializing an object with dynamic properties HHVM needs to pre-reserve the full size of the dynamic property array before inserting…
published 2021-03-11 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-12726
- cvss
- 9.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.4%
- EPSS 1.4% chance of exploitation in 30 days, percentile 72%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Exploit prediction
1.38% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.5 | AV:N/AC:L/Au:N/C:P/I:P/A:P |
Affected products
- Facebook HHVM
Classification
- Weakness
-
- CWE-416 Use After Free
References
-
github.com
/facebook/hhvm/commit/c1c4bb0cf9e076aafaf4ff3515556ef9faf906f3
patch, third-party-advisory
-
hhvm.com
/blog/2020/06/30/security-update.html
vendor-advisory
Sources
- CVE List CVE-2020-1900
- NVD CVE-2020-1900
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.