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Public proof of conceptFix available

CVE-2023-25725

A public proof of concept exists; no exploitation attested.

  • Published2023-02-14
  • Fixed in2.7.3 · 2.6.9 · 2.5.12 · 2.4.22 · 2.2.29 · 2.0.31
  • WeaknessCWE-444

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

HAProxy before 2.7.3 may allow a bypass of access control because HTTP/1 headers are inadvertently lost in some situations, aka "request smuggling." The HTTP header parsers in HAProxy may accept empty header field names, which could be used to truncate the list of HTTP headers and thus make some headers disappear after being parsed and processed for HTTP/1.0 and HTTP/1.1. For HTTP/2 and HTTP/3, the impact is limited because the headers disappear before being parsed and processed, as if they had not been sent by the client. The fixed versions are 2.7.3, 2.6.9, 2.5.12, 2.4.22, 2.2.29, and 2.0.31.

Timeline

dates in UTC
  1. 2023-02-1419:15CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-25725?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-25725?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
HAProxy
BranchAffectedFixed in
2.7≥ 2.7.0, < 2.7.32.7.3
2.6≥ 2.6.0, < 2.6.92.6.9
2.5≥ 2.5.0, < 2.5.122.5.12
2.x≥ 2.3.0, < 2.4.222.4.22
2.x≥ 2.1.0, < 2.2.292.2.29
2.0< 2.0.312.0.31
Debian debian linux
BranchAffectedFixed in
10.0= 10.0no fix published
11.0= 11.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • RHSA-2024:0746 Red Hat Product Security3 products fixed

    Red Hat Security Advisory: new container image: rhceph-5.3

  • RHSA-2023:1325 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.13.0 security update

Full record on NVD

Fix

  1. Update HAProxy to 2.7.3 · 2.6.9 · 2.5.12 · 2.4.22 · 2.2.29 · 2.0.31
  2. Vendor fix Red Hat Product Security RHSA-2024:0746 · 3 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/2789521 and https://access.redhat.com/documentation/en-us/red_hat_ceph_storage/5/html-single/up…
  3. Vendor fix Red Hat Product Security RHSA-2023:1325 · 13 productsFor OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.13/release_notes/ocp-4-1…

Detection

read 2026-10-23 19:23 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifiedkrillingws/LAB-CVE-2023-25725
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Published
2023-02-14
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2023-25725?

HAProxy before 2.7.3 may allow a bypass of access control because HTTP/1 headers are inadvertently lost in some situations, aka "request smuggling." The HTTP header parsers in HAProxy may accept empty header field names, which could be used to truncate the list of HTTP headers and thus make some headers disappear after being parsed and processed for HTTP/1.0 and HTTP/1.1. For HTTP/2 and HTTP/3, the impact is limited because the headers disappear before being parsed and processed, as if they had not been sent by the client. The fixed versions are 2.7.3, 2.6.9, 2.5.12, 2.4.22, 2.2.29, and 2.0.31.

Is CVE-2023-25725 actively exploited?

Active exploitation of CVE-2023-25725 has not been confirmed. Its EPSS score was 5.4% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2023-25725?

CVE-2023-25725 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

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