How severe is CVE-2019-11936?

CVE-2019-11936 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-11936 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-11936?

CVE-2019-11936 primarily affects Facebook Hhvm. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-11936?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2019-11936 published?

CVE-2019-11936 was published on 2019-12-04 and last updated on 2026-06-17.

CVE-2019-11936

CVE-2019-11936 is a critical-severity vulnerability in Facebook Hhvm with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-626.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-626
Affected product: Facebook Hhvm
Published: 2019-12-04
Last modified: 2026-06-17

Description

Various APC functions accept keys containing null bytes as input, leading to premature truncation of input. This issue affects HHVM versions prior to 3.30.12, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.23.1, as well as 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1.

Frequently asked questions

What is CVE-2019-11936?: Various APC functions accept keys containing null bytes as input, leading to premature truncation of input. This issue affects HHVM versions prior to 3.30.12, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.23.1, as well as 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1.
How severe is CVE-2019-11936?: CVE-2019-11936 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-11936 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-11936?: CVE-2019-11936 primarily affects Facebook Hhvm. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-11936?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2019-11936 published?: CVE-2019-11936 was published on 2019-12-04 and last updated on 2026-06-17.

References

Affected products (7)

cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
cpe:2.3:a:facebook:hhvm:4.24.0:*:*:*:*:*:*:*
cpe:2.3:a:facebook:hhvm:4.25.0:*:*:*:*:*:*:*
cpe:2.3:a:facebook:hhvm:4.26.0:*:*:*:*:*:*:*
cpe:2.3:a:facebook:hhvm:4.27.0:*:*:*:*:*:*:*
cpe:2.3:a:facebook:hhvm:4.28.0:*:*:*:*:*:*:*
cpe:2.3:a:facebook:hhvm:4.28.1:*:*:*:*:*:*:*

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