CVE-2020-1899The unserialize() function supported a type code, "S", which was meant to be supported only for APC serialization. This type code allowed…
- 7.5HighCVSS base score
- 1.2%Exploitation in 30 daysEPSS · top 31% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
The unserialize() function supported a type code, "S", which was meant to be supported only for APC serialization. This type code allowed arbitrary memory addresses to be accessed as if they were static StringData objects. 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.
Timeline
ID reserved
By facebook
- 16 months later
· 16 months later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 1.2% · top 31% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- unaffected 4.62.1 – < unspecified
- affected 4.62.0
- unaffected 4.61.1 – < unspecified
- affected 4.61.0
- unaffected 4.60.1 – < unspecified
- affected 4.60.0
- unaffected 4.59.1 – < unspecified
- affected 4.59.0
- unaffected 4.58.2 – < unspecified
- affected 4.58.0 – < unspecified
- unaffected 4.57.1 – < unspecified
- affected 4.57.0
- unaffected 4.56.1 – < unspecified
- affected 4.33.0 – < unspecified
- unaffected 4.32.3 – < unspecified
- affected unspecified – < 4.32.3
References
References2
- https://hhvm.com/blog/2020/06/30/security-update.html (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/facebook/hhvm/commit/1107228a5128d3ca1c4add8ac1635d933cbbe2e9 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2020-12725 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2020-1899)Record last updated .