What’s Vulnerable › Vulnerabilities

CVE-2020-1917

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-10 · updated 2026-06-17
• Weakness: CWE-122

Description

xbuf_format_converter, used as part of exif_read_data, was appending a terminating null character to the generated string, but was not using its standard append char function. As a result, if the buffer was full, it would result in an out-of-bounds write. 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.

Affected products

• Facebook HHVM: before 4.56.3; from 4.57.0 before 4.80.2; from 4.81.0 before 4.93.2; 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0 — fixed in 4.56.3, 4.80.2, 4.93.2

How to fix

Upgrade to a fixed version: Facebook HHVM 4.56.3, 4.80.2, 4.93.2. Check the vendor advisory for mitigations.

References

• https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca
• https://hhvm.com/blog/2021/02/25/security-update.html
• https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca
• https://hhvm.com/blog/2021/02/25/security-update.html

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