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).
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | haproxy | 2.0.6-1 | — |
| Debian 13 | haproxy | 2.0.6-1 | — |
| Debian 12 | haproxy | 2.0.6-1 | — |
| Debian 9 | haproxy | 1.7.5-2+deb9u1 | DLA-3034-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | haproxy | 1.8.8-1ubuntu0.7 | USN-4174-1 |
| Ubuntu 16.04 LTS | haproxy | 1.6.3-1ubuntu0.3 | USN-4174-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | haproxy | 1.8.23-3.el8 | RHSA-2020:1725 |
| RHEL 3 | rh-haproxy18-haproxy +1 | 1.8.24-2.el7 | RHSA-2020:2265 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat OpenShift 4 | haproxy +1 | 2.0.13-3.el7 | RHSA-2020:1936 |
| Red Hat OpenShift 3 | haproxy +1 | 1.8.23-3.el7 | RHSA-2020:1287 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP1 | haproxy | 2.0.10+git0.ac198b92-8.8.1 | SUSE-SU-2019:3126-1 |
| SLES 15 | haproxy | 2.0.10+git0.ac198b92-3.15.1 | SUSE-SU-2019:3125-1 |
| SLES 12 SP5 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SLES 12 SP4 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SLES 12 SP3 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE OpenStack Cloud Crowbar 9 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SUSE OpenStack Cloud Crowbar 8 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SUSE OpenStack Cloud 9 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SUSE OpenStack Cloud 8 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SUSE OpenStack Cloud 7 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
| SUSE HPE Helion OpenStack 8 | haproxy | 1.6.11-11.3.1 | SUSE-SU-2019:3288-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | haproxy | 2.4.4+git0.acb1d0bea-1.2 | openSUSE-SU-2024:10839-1 |
| openSUSE Leap 15.1 | haproxy | 2.0.10+git0.ac198b92-lp151.2.6.1 | openSUSE-SU-2019:2645-1 |
| openSUSE Leap 15.0 | haproxy | 2.0.10+git0.ac198b92-lp150.2.16.1 | openSUSE-SU-2019:2626-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | haproxy | 1.8.23-3.el8 | ELSA-2020-1725 |
Advisories 14
- WID-SEC-2024-0054 IBM Security Verify Access: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 16, 2026
- RHSA-2020:2265 Red Hat Security Advisory: rh-haproxy18-haproxy security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2020:1725 Red Hat Security Advisory: haproxy security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2020:1936 Red Hat Security Advisory: OpenShift Container Platform 4.4.3 haproxy security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2020:1287 Red Hat Security Advisory: OpenShift Container Platform 3.11 security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- DLA-3034-1 haproxy - security update Debian Security (DSA / DLA) · Mar 9, 2026
- USN-4174-1 haproxy vulnerability Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2024:10839-1 haproxy-2.4.4+git0.acb1d0bea-1.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:3125-1 Security update for haproxy SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:3126-1 Security update for haproxy SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:2626-1 Security update for haproxy SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:3288-1 Security update for haproxy SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:2645-1 Security update for haproxy SUSE / openSUSE Security Updates · May 7, 2025
- ELSA-2020-1725 Moderate: haproxy security, bug fix, and enhancement update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 5, 2020
References
- https://www.mail-archive.com/haproxy%40formilux.org/msg34926.html
- https://nathandavison.com/blog/haproxy-http-request-smuggling
- https://git.haproxy.org/?p=haproxy-2.0.git%3Ba=commit%3Bh=196a7df44d8129d1adc795da020b722614d6a581
- USN-4174-1 vendor-advisory
- openSUSE-SU-2019:2626 vendor-advisory
- openSUSE-SU-2019:2645 vendor-advisory
- [debian-lts-announce] 20220530 [SECURITY] [DLA 3034-1] haproxy security update mailing-list