How severe is CVE-2016-1000109?

CVE-2016-1000109 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2016-1000109 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-1000109?

CVE-2016-1000109 affects Facebook Hhvm. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-1000109?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2016-1000109 published?

CVE-2016-1000109 was published on 2020-02-19 and last updated on 2026-06-17.

CVE-2016-1000109

CVE-2016-1000109 is a medium-severity vulnerability in Facebook Hhvm with a CVSS 3.x base score of 5.3. 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-665.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-665
Affected product: Facebook Hhvm
Published: 2020-02-19
Last modified: 2026-06-17

Description

HHVM does not attempt to address RFC 3875 section 4.1.18 namespace conflicts and therefore does not protect CGI applications from the presence of untrusted client data in the HTTP_PROXY environment variable, which might allow remote attackers to redirect a CGI application's outbound HTTP traffic to an arbitrary proxy server via a crafted Proxy header in an HTTP request, aka an "httpoxy" issue. This issue affects HHVM versions prior to 3.9.6, all versions between 3.10.0 and 3.12.4 (inclusive), and all versions between 3.13.0 and 3.14.2 (inclusive).

Frequently asked questions

What is CVE-2016-1000109?: HHVM does not attempt to address RFC 3875 section 4.1.18 namespace conflicts and therefore does not protect CGI applications from the presence of untrusted client data in the HTTP_PROXY environment variable, which might allow remote attackers to redirect a CGI application's outbound HTTP traffic to an arbitrary proxy server via a crafted Proxy header in an HTTP request, aka an "httpoxy" issue. This issue affects HHVM versions prior to 3.9.6, all versions between 3.10.0 and 3.12.4 (inclusive), and all versions between 3.13.0 and 3.14.2 (inclusive).
How severe is CVE-2016-1000109?: CVE-2016-1000109 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2016-1000109 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-1000109?: CVE-2016-1000109 affects Facebook Hhvm. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-1000109?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-1000109 published?: CVE-2016-1000109 was published on 2020-02-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*

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