Information disclosure in HAProxy
Priority MEDIUM 41CWE-200Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 1 fixed, 5 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-200.
Summary
An information leak vulnerability was discovered in HAProxy 2.1, 2.2 before 2.2.27, 2.3, 2.4 before 2.4.21, 2.5 before 2.5.11, 2.6 before 2.6.8, 2.7 before 2.7.1. There are 5 bytes left uninitialized in the connection buffer when encoding the FCGI_BEGIN_REQUEST record. Sensitive data may be disclosed to configured FastCGI backends in an unexpected way.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01201 68th percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 5 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | HAProxy | HAProxy 2.8, HAProxy 2.7.1, HAProxy 2.6.8, HAProxy 2.5.11, HAProxy 2.4.21, HAProxy 2.2.27 | — | No fix listed | CNA |
- HAProxy Vendor— Affected HAProxy 2.8, HAProxy 2.7.1, HAProxy 2.6.8, HAProxy 2.5.11, HAProxy 2.4.21, HAProxy 2.2.27 Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:* | 2.2.0 to before 2.2.27; 2.4.0 – 2.4.21; 2.5.0 – 2.5.11; 2.6.0 – 2.6.8 | Vulnerable | HAProxy |
| cpe:2.3:a:haproxy:haproxy:2.1.0:*:*:*:*:*:*:* | 2.1.0 | Vulnerable | HAProxy |
| cpe:2.3:a:haproxy:haproxy:2.3.0:*:*:*:*:*:*:* | 2.3.0 | Vulnerable | HAProxy |
| cpe:2.3:a:haproxy:haproxy:2.7.0:*:*:*:*:*:*:* | 2.7.0 | Vulnerable | HAProxy |
- cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:* Versions 2.2.0 to before 2.2.27; 2.4.0 – 2.4.21; 2.5.0 – 2.5.11; 2.6.0 – 2.6.8 Vulnerable ·HAProxy
- cpe:2.3:a:haproxy:haproxy:2.1.0:*:*:*:*:*:*:* Versions 2.1.0 Vulnerable ·HAProxy
- cpe:2.3:a:haproxy:haproxy:2.3.0:*:*:*:*:*:*:* Versions 2.3.0 Vulnerable ·HAProxy
- cpe:2.3:a:haproxy:haproxy:2.7.0:*:*:*:*:*:*:* Versions 2.7.0 Vulnerable ·HAProxy
Remediation
Red Hat 1 advisory
- RHSA-2023:6496 Released 2023-11-07 · Red Hat rating Moderatehaproxy security and bug fix update
- Red Hat Enterprise Linux AppStream (v. 9) haproxy-2.4.22-1.el9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Ceph Storage 5 | Affected | No fix yet |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat OpenShift Container Platform 3.11 | Affected | No fix planned: Out of support scope |
| Red Hat OpenShift Container Platform 4 | Affected | No fix planned: Will not fix |
| Red Hat Software Collections | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2023:6496 |
Not affected: 1 product
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2023-0836
- 2026-10-03 Alias added: GHSA-xhfw-qhxr-hjhq
References
More Haproxy vulnerabilities
- TI-2020-08973 In hpack_dht_insert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before… CVSS 3.1HIGH 8.8
- TI-2023-21094 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… CVSS 3.1HIGH 7.2
- TI-2019-10602 HAProxy through 2.0.2 allows attackers to cause a denial of service (ha_panic) via… CVSS 3.0HIGH 7.5
- TI-2021-17418 An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be… CVSS 3.1HIGH 7.5
- TI-2016-04651 HAproxy 1.6.x before 1.6.6, when a deny comes from a reqdeny rule, allows remote… CVSS 3.0HIGH 7.5
- TI-2026-25946 An issue was discovered in HAProxy before 3.3.6. CVSS 3.1MEDIUM 5.8
Sources
- CVE-2023-0836 · CVE Program
- CVE-2023-0836 · NVD
- FIRST EPSS
- GHSA-xhfw-qhxr-hjhq · GitHub Advisory Database · CC BY 4.0
- CVE-2023-0836 · Red Hat security data · CC BY 4.0
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