CVE-2019-16786
HIGHEPSS 83th pctlDescription
Waitress through version 1.3.1 would parse the Transfer-Encoding header and only look for a single string value, if that value was not chunked it would fall through and use the Content-Length header instead. According to the HTTP standard Transfer-Encoding should be a comma separated list, with the inner-most encoding first, followed by any further transfer codings, ending with chunked. Requests sent with: "Transfer-Encoding: gzip, chunked" would incorrectly get ignored, and the request would use a Content-Length header instead to determine the body size of the HTTP message. This could allow for Waitress to treat a single request as multiple requests in the case of HTTP pipelining. This issue is fixed in Waitress 1.4.0.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N
Exploit Intelligence
Elevated risk: more likely to be exploited than 83% of all known CVEs.
References
Related Vulnerabilities
Other CWE-444 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-22536 | Critical | 10.0 | 98% | KEV | - |
| CVE-2025-61884 | High | 7.5 | 98% | KEV + Ransom | - |
| CVE-2020-9490 | High | 7.5 | 90% | - | Fix |
| CVE-2023-41265 | Critical | 9.6 | 84% | KEV + Ransom | - |
| CVE-2023-25690 | Critical | 9.8 | 84% | - | Fix |
| CVE-2022-32214 | Medium | 6.5 | 81% | - | Fix |
Common questions
How do I fix CVE-2019-16786?
Upgrade waitress on debian 11 to 1.4.1-1 or later.
Is CVE-2019-16786 being actively exploited?
Not that we know of. CVE-2019-16786 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.5% is the estimated probability that it will be exploited in the next 30 days. That is higher than 83% of all scored CVEs.
How severe is CVE-2019-16786?
CVE-2019-16786 has a CVSS v3 base score of 7.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2019-16786 affect?
Published advisories record a fix for waitress (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.