Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2019-18277

28
FAUCET Score

CVE-2019-18277 describes a flaw in HAProxy versions prior to 2.0.6, where the load balancer failed to properly reject HTTP messages with an invalid "transfer-encoding" header in legacy mode. This vulnerability, while limited in direct impact, could facilitate HTTP request smuggling attacks when combined with the "http-reuse always" setting and a lenient downstream parser. Rated with a CVSS score of 7.5 (High), it has a low attack complexity and does not require user interaction, potentially leading to high integrity impact. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 2.0.6CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
10.02%
Probability of exploitation in next 30 days
EPSS Percentile
95.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.1002 is in the 92nd percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: haproxy-0:1.8.23-3.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat OpenShift Container Platform 3.11Fixed in: haproxy-0:1.8.23-3.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat OpenShift Container Platform 4.4Fixed in: haproxy-0:2.0.13-3.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-haproxy18-haproxy-0:1.8.24-2.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSFixed in: rh-haproxy18-haproxy-0:1.8.24-2.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-haproxy18-haproxy-0:1.8.24-2.el7
View patch
redhatend of lifevia redhat_api
Product: Red Hat OpenShift Container Platform 3.10Fixed in: haproxy
redhatend of lifevia redhat_api
Product: Red Hat OpenShift Container Platform 3.9Fixed in: haproxy

Vendor Advisories (1)

redhatCVE-2019-18277Moderate

haproxy: HTTP request smuggling issue with transfer-encoding header containing an obfuscated "chunked" value

Sep 13, 2019

References

lists.opensuse.org / opensuse-security-announce/2019-12/msg00016.html
lists.opensuse.org / opensuse-security-announce/2019-12/msg00019.html
git.haproxy.org
lists.debian.org / debian-lts-announce/2022/05/msg00045.html
nathandavison.com / blog/haproxy-http-request-smuggling
ExploitThird Party Advisory
usn.ubuntu.com / 4174-1
mail-archive.com / haproxy%40formilux.org/msg34926.html