CVE-2020-1921 Memory corruption in HHVM

What is CVE-2020-1921?

CVE-2020-1921 is a high-severity memory corruption vulnerability in Facebook HHVM, published on 10 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In the crypt function, we attempt to null terminate a buffer using the size of the input salt without validating that the offset is within the buffer. This issue affects HHVM versions prior to 4.56.3, all versions between 4.57.0 and 4.80.1, all versions between 4.81.0 and 4.93.1, and versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0.

Weakness: CWE-787, CWE-121

Which versions are affected by CVE-2020-1921?

It affects 1 product.

Products include Facebook Hhvm.

How do I fix CVE-2020-1921?

No fix has been published for CVE-2020-1921 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2020-1921 being exploited?

There is no known exploitation of CVE-2020-1921 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-2020-1900 Use after free in HHVM 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

Sources

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

Also known as GHSA-x3g2-p3p4-fghf, UBUNTU-CVE-2020-1921.