CVE-2020-1900
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.38%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.38% probability · 72th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- facebook/hhvm
- Source
- cve-assign@fb.com
EPSS 1.4% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/facebook/hhvm/commit/c1c4bb0cf9e076aafaf4ff3515556ef9faf906f3Patch, Third Party Advisory
- https://hhvm.com/blog/2020/06/30/security-update.htmlVendor Advisory
- https://github.com/facebook/hhvm/commit/c1c4bb0cf9e076aafaf4ff3515556ef9faf906f3Patch, Third Party Advisory
- https://hhvm.com/blog/2020/06/30/security-update.htmlVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.