{"id":"CVE-2020-1900","aliases":["EUVD-2020-12726","GHSA-g7r3-m2h7-28vw","UBUNTU-CVE-2020-1900"],"status":"published","title":"When unserializing an object with dynamic properties HHVM needs to pre-reserve the full size of...","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.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-08","score":0.01384,"percentile":0.72375,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-416"],"published":"2021-03-11T00:55:20Z","modified":"2026-11-04T02:45:13Z","affected":[{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"hhvm","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.11.0+dfsg-1","3.11.1+dfsg-1","3.11.1+dfsg-1ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"hhvm","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.21.0+dfsg-2","3.21.0+dfsg-2build1","3.21.0+dfsg-2build2","3.21.0+dfsg-2build3","3.21.0+dfsg-2ubuntu2"]}],"products":[{"vendor":"facebook","product":"hhvm"}],"references":[{"url":"https://hhvm.com/blog/2020/06/30/security-update.html","tags":["x_refsource_CONFIRM","x_transferred","Vendor Advisory","advisory","report"]},{"url":"https://github.com/facebook/hhvm/commit/c1c4bb0cf9e076aafaf4ff3515556ef9faf906f3","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","fix","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-1900"},{"url":"https://github.com/advisories/GHSA-g7r3-m2h7-28vw"},{"url":"https://ubuntu.com/security/CVE-2020-1900","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2020-1900","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2020-1900","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.","status":"published","published":"2021-03-11T00:55:20Z","modified":"2024-08-04T06:54:00.541Z","cwes":["CWE-416"],"updated_at":"2026-11-02T14:35:56.638833Z"}],"euvd":[{"id":"EUVD-2020-12726","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.","status":"published","published":"2021-03-11T00:55:20Z","modified":"2024-08-04T06:54:00Z","updated_at":"2026-11-03T03:08:10.95725Z"}],"ghsa":[{"id":"GHSA-g7r3-m2h7-28vw","title":"When unserializing an object with dynamic properties HHVM needs to pre-reserve the full size of...","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.","status":"published","published":"2022-05-24T17:44:15Z","modified":"2023-01-29T05:06:00Z","cwes":["CWE-416"],"updated_at":"2026-11-02T14:45:55.677123Z"}],"nvd":[{"id":"CVE-2020-1900","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.","status":"published","published":"2021-03-11T01:15:14.49Z","modified":"2026-06-17T03:02:34.887Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"},{"version":"2.0","score":7.5,"vector":"AV:N/AC:L/Au:N/C:P/I:P/A:P","level":"high","assessor":"primary"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:06:37.687844Z"}],"osv":[{"id":"CVE-2020-1900","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.","status":"published","published":"2021-03-11T01:15:14.49Z","modified":"2026-11-04T07:06:59.156699579Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-04T07:32:23.735279Z"},{"id":"UBUNTU-CVE-2020-1900","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.","status":"published","published":"2021-03-11T01:15:00Z","modified":"2026-04-22T12:32:10.813909Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:54:23.344108Z"}]}}