Every CVE Search/ Get API key

CVE-2021-39242

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It...

7.5 HighFix available

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

2.23%Up 1.4 points since Aug 18, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
CVE-2021-39242
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:P/A:N
Weakness
CWE-755
Updated
2026-11-02
CVE List No score

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
CVE-2021-39242
Updated
2026-11-02
EUVDEUVD-2021-25604 No score

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
EUVD-2021-25604
Updated
2026-11-03
GitHub AdvisoriesGHSA-gh3m-9h22-r3r5 No score

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It...

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
GHSA-gh3m-9h22-r3r5
Weakness
CWE-755
Updated
2026-11-02
OSV 7.5

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
CVE-2021-39242
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-39242 7.5

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
DEBIAN-CVE-2021-39242
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
Show 4 moreShow less
OSVOESA-2021-1333 7.5

haproxy security update

HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is particularly suited for very high traffic web sites and powers quite a number of the world's most visited ones.

Security Fix(es):

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It does not ensure that the scheme and path portions of a URI have the expected characters. For example, the authority field (as observed on a target HTTP/2 server) might differ from what the routing rules were intended to achieve.(CVE-2021-39240)

An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.(CVE-2021-39241)

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.(CVE-2021-39242)

Record
OESA-2021-1333
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVRHSA-2021:4118 7.5

Red Hat Security Advisory: OpenShift Container Platform 4.9.6 packages and security update

Record
RHSA-2021:4118
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
OSVRHSA-2021:5208 7.5

Red Hat Security Advisory: OpenShift Container Platform 4.8.25 security update

Record
RHSA-2021:5208
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
OSVBIT-haproxy-2021-39242 No score

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Record
BIT-haproxy-2021-39242
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
haproxy
Bitnami
 2.2.0 up to 2.2.16, 2.3.0 up to 2.3.13, 2.4.0 up to 2.4.3
2.2.162.3.132.4.3
haproxy
Debian:12
 before 2.2.16-1
2.2.16-1
haproxy
Debian:13
 before 2.2.16-1
2.2.16-1
haproxy
Debian:14
 before 2.2.16-1
2.2.16-1
haproxy
Debian:11
From an advisory covering 3 CVEs
 before 2.2.9-2+deb11u1, plus listed versions
2.2.9-22.2.9-2+deb11u1~bpo10+1
2.2.9-2+deb11u1
haproxy
openEuler:20.03-LTS-SP1
From an advisory covering 3 CVEs
 before 2.2.16-1.oe1
2.2.16-1.oe1
haproxy
openEuler:20.03-LTS-SP2
From an advisory covering 3 CVEs
 before 2.2.16-1.oe1
2.2.16-1.oe1
haproxy
Red Hat:openshift:4.9::el8
From an advisory covering 4 CVEs
 before 0:2.2.15-2.el8
0:2.2.15-2.el8
haproxy-debugsource
Red Hat:openshift:4.9::el8
From an advisory covering 4 CVEs
 before 0:2.2.15-2.el8
0:2.2.15-2.el8
haproxy
Red Hat:openshift:4.8::el7
From an advisory covering 4 CVEs
 before 0:2.2.13-2.el7
0:2.2.13-2.el7
haproxy-debuginfo
Red Hat:openshift:4.8::el7
From an advisory covering 4 CVEs
 before 0:2.2.13-2.el7
0:2.2.13-2.el7
haproxy
Red Hat:openshift:4.8::el8
From an advisory covering 4 CVEs
 before 0:2.2.13-2.el8
0:2.2.13-2.el8
haproxy-debugsource
Red Hat:openshift:4.8::el8
From an advisory covering 4 CVEs
 before 0:2.2.13-2.el8
0:2.2.13-2.el8

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-39242 is a high vulnerability (CVSS 7.5) in Haproxy, published August 17, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.23%, the 82nd percentile. Fixed in haproxy 2.2.16.

References

Show 29 moreShow less
Pages All vulnerabilities Browse Docs Sources Guide Get API key
MoveEnter Open