How severe is CVE-2016-6287?

CVE-2016-6287 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2016-6287 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-2016-6287?

CVE-2016-6287 affects Call-cc Http-client. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-6287?

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

When was CVE-2016-6287 published?

CVE-2016-6287 was published on 2017-01-10 and last updated on 2026-06-17.

CVE-2016-6287

CVE-2016-6287 is a high-severity vulnerability in Call-cc Http-client with a CVSS 3.x base score of 7.5. 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-19.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-19
Affected product: Call-cc Http-client
Published: 2017-01-10
Last modified: 2026-06-17

Description

The "http-client" egg always used a HTTP_PROXY environment variable to determine whether HTTP traffic should be routed via a proxy, even when running as a CGI process. Under several web servers this would mean a user-supplied "Proxy" header could allow an attacker to direct all HTTP requests through a proxy (also known as a "httpoxy" attack). This affects all versions of http-client before 0.10.

Frequently asked questions

What is CVE-2016-6287?: The "http-client" egg always used a HTTP_PROXY environment variable to determine whether HTTP traffic should be routed via a proxy, even when running as a CGI process. Under several web servers this would mean a user-supplied "Proxy" header could allow an attacker to direct all HTTP requests through a proxy (also known as a "httpoxy" attack). This affects all versions of http-client before 0.10.
How severe is CVE-2016-6287?: CVE-2016-6287 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2016-6287 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-2016-6287?: CVE-2016-6287 affects Call-cc Http-client. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-6287?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-6287 published?: CVE-2016-6287 was published on 2017-01-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:call-cc:http-client:*:*:*:*:*:*:*:*

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CVE-2016-6286 — High (CVSS 7.5): The "spiffy-cgi-handlers" egg would convert a nonexistent "Proxy" header to the HTTP_PROXY environment variable, which…

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