CVE-2019-16786

HIGHNVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.1 under NVD CVSS v3. EPSS exploit probability: 0.9%, top 24% 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
7.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 7.1Exploit: NoneExposed: 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)
EPSS
83.1%
KEV
Not listed

Published

December 20, 2019

Last Modified

November 21, 2024

References (16)

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

(1 across 1 ecosystem)
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.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 9× in last 7d / 41× 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.

  1. 2026-07-11 08:24 UTCEPSS rescore
  2. 2026-07-11 08:24 UTCEPSS rescore
  3. 2026-07-09 19:06 UTCEPSS rescore
  4. 2026-07-08 15:11 UTCEPSS rescore
  5. 2026-07-07 13:43 UTCEPSS rescore
  6. 2026-07-06 16:25 UTCEPSS rescore
  7. 2026-07-06 16:25 UTCEPSS rescore
  8. 2026-07-06 02:20 UTCEPSS rescore
  9. 2026-07-05 02:27 UTCEPSS rescore
  10. 2026-07-04 06:28 UTCEPSS rescore
  11. 2026-07-02 14:00 UTCOSV refresh
  12. 2026-07-01 15:03 UTCEPSS rescore
  13. 2026-07-01 15:03 UTCEPSS rescore
  14. 2026-06-30 23:20 UTCEPSS rescore
  15. 2026-06-29 14:03 UTCEPSS rescore
  16. 2026-06-28 14:04 UTCEPSS rescore
  17. 2026-06-28 04:54 UTCEPSS rescore
  18. 2026-06-28 04:54 UTCEPSS rescore
  19. 2026-06-27 03:06 UTCEPSS rescore
  20. 2026-06-25 13:47 UTCEPSS rescore
  21. 2026-06-25 13:47 UTCEPSS rescore
  22. 2026-06-24 14:03 UTCEPSS rescore
  23. 2026-06-24 14:03 UTCEPSS rescore
  24. 2026-06-23 21:31 UTCEPSS rescore
  25. 2026-06-23 21:30 UTCEPSS rescore
Show 49 more
  1. 2026-06-22 14:23 UTCEPSS rescore
  2. 2026-06-21 14:54 UTCEPSS rescore
  3. 2026-06-21 14:54 UTCEPSS rescore
  4. 2026-06-21 01:57 UTCEPSS rescore
  5. 2026-06-21 01:57 UTCEPSS rescore
  6. 2026-06-19 19:23 UTCEPSS rescore
  7. 2026-06-19 19:23 UTCEPSS rescore
  8. 2026-06-18 17:50 UTCEPSS rescore
  9. 2026-06-17 17:50 UTCEPSS rescore
  10. 2026-06-16 17:50 UTCEPSS rescore
  11. 2026-06-15 17:45 UTCEPSS rescore
  12. 2026-06-14 23:15 UTCEPSS rescore
  13. 2026-06-14 23:15 UTCEPSS rescore
  14. 2026-06-14 12:13 UTCOSV refresh
  15. 2026-06-13 22:58 UTCEPSS rescore
  16. 2026-06-12 23:09 UTCEPSS rescore
  17. 2026-06-11 13:58 UTCEPSS rescore
  18. 2026-06-10 22:16 UTCEPSS rescore
  19. 2026-06-10 13:19 UTCEPSS rescore
  20. 2026-06-08 14:15 UTCEPSS rescore
  21. 2026-06-07 15:23 UTCEPSS rescore
  22. 2026-06-07 15:23 UTCEPSS rescore
  23. 2026-06-06 13:45 UTCEPSS rescore
  24. 2026-06-06 13:45 UTCEPSS rescore
  25. 2026-06-05 22:45 UTCEPSS rescore
  26. 2026-06-05 22:45 UTCEPSS rescore
  27. 2026-06-05 06:08 UTCEPSS rescore
  28. 2026-06-05 06:08 UTCEPSS rescore
  29. 2026-06-04 13:10 UTCEPSS rescore
  30. 2026-06-04 13:10 UTCEPSS rescore
  31. 2026-06-02 20:11 UTCEPSS rescore
  32. 2026-06-02 20:11 UTCEPSS rescore
  33. 2026-06-01 13:50 UTCEPSS rescore
  34. 2026-06-01 13:50 UTCEPSS rescore
  35. 2026-05-31 22:29 UTCEPSS rescore
  36. 2026-05-31 22:29 UTCEPSS rescore
  37. 2026-05-31 00:14 UTCEPSS rescore
  38. 2026-05-31 00:14 UTCEPSS rescore
  39. 2026-05-29 13:42 UTCEPSS rescore
  40. 2026-05-28 13:43 UTCEPSS rescore
  41. 2026-05-27 13:38 UTCEPSS rescore
  42. 2026-05-27 10:00 UTCEG score recompute
  43. 2026-05-27 10:00 UTCVendor advisory
  44. 2026-05-26 13:42 UTCEPSS rescore
  45. 2026-05-26 13:42 UTCEPSS rescore
  46. 2026-05-26 07:17 UTCEPSS rescore
  47. 2026-05-26 07:17 UTCEPSS rescore
  48. 2026-05-26 07:17 UTCEPSS rescore
  49. 2026-05-24 22:56 UTCOSV refresh

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 83.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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.

Dependency Blast Radius

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