CVE-2019-16785
HTTP Request Smuggling: LF vs CRLF handling in Waitress
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.
Timeline
ID reserved
By GitHub_M
- 3 months later
· 3 months later
Published
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N |
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 2.5% · top 15% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPIwaitressGHSA-pg36-wpm5-g57p (opens in a new tab)
References (8)
- FEDORA-2020-bdcc8ffc24 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2020-65a7744e38 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- RHSA-2020:0720 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- https://www.oracle.com/security-alerts/cpuapr2022.html (opens in a new tab)x_refsource_MISCx_transferred
- https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/Pylons/waitress/security/advisories/GHSA-pg36-wpm5-g57p (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/Pylons/waitress/commit/8eba394ad75deaf9e5cd15b78a3d16b12e6b0eba (opens in a new tab)x_refsource_MISCx_transferred
- [debian-lts-announce] 20220512 [SECURITY] [DLA 3000-1] waitress security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-pg36-wpm5-g57p (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2019-16785)Record last updated .