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CVE-2023-40225

21
FAUCET Score

CVE-2023-40225 describes a vulnerability in HAProxy versions up to 2.8.2 where it improperly forwards empty Content-Length headers, potentially leading an HTTP/1 backend server to misinterpret subsequent data as an additional request. This issue carries a CVSS score of 7.2 (High), indicating a network-based attack with low complexity that could lead to partial confidentiality and integrity impacts. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.0.32CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
>= 2.2.0, <= 2.2.30CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
>= 2.4.0, <= 2.4.23CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
>= 2.5.0, < 2.6.15CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
>= 2.7.0, < 2.7.10CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.2HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.81%
Probability of exploitation in next 30 days
EPSS Percentile
76.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0181 is in the 59th percentile among its peer group of 51,553 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 (10)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: cbl2 haproxy 2.4.24-1 on CBL Mariner 2.0Fixed in: 2.4.24-1
microsoftpatch availablevia msrc
Product: 17219-16823Fixed in: 2.4.24-1
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: haproxy-0:2.4.22-3.el9_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9.2 Extended Update SupportFixed in: haproxy-0:2.4.17-6.el9_2.2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat OpenShift Container Platform 4.11Fixed in: haproxy-0:2.2.24-4.rhaos4.11.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat OpenShift Container Platform 4.12Fixed in: haproxy-0:2.2.24-4.rhaos4.12.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat OpenShift Container Platform 4.13Fixed in: haproxy-0:2.2.24-4.rhaos4.13.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat OpenShift Container Platform 4.14Fixed in: haproxy-0:2.6.13-2.rhaos4.14.el8
View patch
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-haproxy18-haproxy

Vendor Advisories (2)

redhatCVE-2023-40225Moderate

haproxy: Proxy forwards malformed empty Content-Length headers

Aug 10, 2023
microsoft2023-Aug/CVE-2023-40225Important

HAProxy through 2.0.32 2.1.x and 2.2.x through 2.2.30 2.3.x and 2.4.x through 2.4.23 2.5.x and 2.6.x before 2.6.15 2.7.x before 2.7.10 and 2.8.x before 2.8.2 forwards empty Content-Length headers violating RFC 9110 section 8.6. In uncommon cases an HTTP/1 server behind HAProxy may interpret the payload as an extra request.

Aug 8, 2023

References

cwe.mitre.org / data/definitions/436.html
Technical Description
github.com / haproxy/haproxy/commit/6492f1f29d738457ea9f382aca54537f35f9d856
Patch
github.com / haproxy/haproxy/issues/2237
ExploitIssue TrackingVendor Advisory
haproxy.org / download/2.6/src/CHANGELOG
Release Notes
haproxy.org / download/2.7/src/CHANGELOG
Release Notes
haproxy.org / download/2.8/src/CHANGELOG
Release Notes