Use After Free in Facebook Hhvm
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. 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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.014 (71.7th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 72nd percentile — 71.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000
Affected products
- Facebook Hhvm — versions 4.58.2, 4.60.1, unspecified
Weakness classification (CWE)
References
- hhvm.com/blog/2020/06/30/security-update.html (Vendor Advisory)
- github.com/facebook/hhvm/commit/c1c4bb0cf9e076aafaf4ff3515556ef9faf906f3 (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2020-1900?
- CVE-2020-1900 is a critical-severity vulnerability in Facebook Hhvm, classified under Use After Free. CVSS score: 9.8/10. Published 2021-03-11.
- How severe is CVE-2020-1900?
- Critical severity. CVSS v3 base score is 9.8 out of 10.