CVE-2019-18277A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were…
- 7.5HighCVSS base score
- 10.1%Exploitation in 30 daysEPSS · top 4.3% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if combined with the "http-reuse always" setting, it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-length header as soon as it saw a transfer-encoding one (even if not entirely valid according to the specification).
Timeline
ID reserved
By mitre
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 |
|---|---|---|---|
| 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)
- 10.1% · top 4.3% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
n/a
- affected n/a
References
References7
- https://www.mail-archive.com/haproxy%40formilux.org/msg34926.html (opens in a new tab)x_refsource_MISCx_transferred
- https://nathandavison.com/blog/haproxy-http-request-smuggling (opens in a new tab)x_refsource_MISCx_transferred
- https://git.haproxy.org/?p=haproxy-2.0.git%3Ba=commit%3Bh=196a7df44d8129d1adc795da020b722614d6a581 (opens in a new tab)x_refsource_MISCx_transferred
- USN-4174-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- openSUSE-SU-2019:2626 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- openSUSE-SU-2019:2645 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- [debian-lts-announce] 20220530 [SECURITY] [DLA 3034-1] haproxy 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)
- EUVD EUVD-2019-8066 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2019-18277)Record last updated .