CVE-2020-1900 Use after free in HHVM

What is CVE-2020-1900?

CVE-2020-1900 is a critical use after free vulnerability in Facebook HHVM, published on 11 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-416

Which versions are affected by CVE-2020-1900?

It affects 1 product.

Products include Facebook Hhvm.

How do I fix CVE-2020-1900?

No fix has been published for CVE-2020-1900 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2020-1900 being exploited?

There is no known exploitation of CVE-2020-1900 in the wild and no public exploit code.

Other vulnerabilities in Facebook HHVM

• CVE-2022-36937 HHVM 4.172.0 and all prior versions use TLS 1.0 for secure connections when handling tls:// URLs in the stream extension. Critical 9.8
• CVE-2020-1916 Integer overflow in HHVM Critical 9.8
• CVE-2020-1917 Memory corruption in HHVM Critical 9.8
• CVE-2021-24025 Integer overflow in HHVM Critical 9.8
• CVE-2016-1000004 Other in n/a Critical 9.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-g7r3-m2h7-28vw, UBUNTU-CVE-2020-1900.