CVE-2019-16786

HIGHNVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.1 under NVD CVSS v3. EPSS exploit probability: 2.5%, top 17% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 7.1Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
7.1
EG Score
7.1(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity71% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
83%
KEV
Not listed

Published

December 20, 2019

Last Modified

November 21, 2024

References (16)

Vendor Advisories for CVE-2019-16786(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatquay/quay-rhel8:v3.4.0-512021-02-04redhat
redhatpython-waitress-0:1.4.2-1.el8ost2020-03-05redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(6 across 6 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
waitress—1.4.1-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
waitress—1.4.1-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
waitress—1.4.1-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
waitress—1.4.1-1—
Debian:9(1)
PackageVulnerable rangeFixed inDependents
waitress1.0.1-11.0.1-1+deb9u1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
waitress0.1 ... 1.3.0 (36 versions)1.3.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 6× in last 7d / 23× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 124 total refreshes for this CVE.

  1. 2026-08-25 13:45 UTCEPSS rescore
  2. 2026-08-24 14:11 UTCEPSS rescore
  3. 2026-08-21 23:45 UTCEPSS rescore
  4. 2026-08-21 08:14 UTCOSV refresh
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  16. 2026-08-05 21:51 UTCOSV refresh
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  4. 2026-07-23 01:41 UTCEG score recompute
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  11. 2026-07-19 23:19 UTCOSV refresh
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  24. 2026-07-12 05:43 UTCEPSS rescore
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  26. 2026-07-11 08:24 UTCEPSS rescore
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  28. 2026-07-09 19:06 UTCEPSS rescore
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  36. 2026-07-02 14:00 UTCOSV refresh
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  64. 2026-06-14 12:13 UTCOSV refresh
  65. 2026-06-13 22:58 UTCEPSS rescore
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  75. 2026-06-05 22:45 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2019-16786?
CVE-2019-16786 is a high vulnerability published on December 20, 2019. 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…
When was CVE-2019-16786 disclosed?
CVE-2019-16786 was first published in the National Vulnerability Database on December 20, 2019, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2019-16786 actively exploited?
CVE-2019-16786 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 17.4% of all scored CVEs.
What is the CVSS score of CVE-2019-16786?
CVE-2019-16786 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2019-16786?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2019-16786, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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