How severe is CVE-2023-0836?

CVE-2023-0836 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2023-0836 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-0836?

CVE-2023-0836 primarily affects Haproxy. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-0836?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-0836 published?

CVE-2023-0836 was published on 2023-03-29 and last updated on 2026-06-17.

CVE-2023-0836

CVE-2023-0836 is a high-severity vulnerability in Haproxy with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Haproxy
Published: 2023-03-29
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2023-0836?: 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.
How severe is CVE-2023-0836?: CVE-2023-0836 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2023-0836 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-0836?: CVE-2023-0836 primarily affects Haproxy. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-0836?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-0836 published?: CVE-2023-0836 was published on 2023-03-29 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:haproxy:haproxy:2.1.0:*:*:*:*:*:*:*
cpe:2.3:a:haproxy:haproxy:2.3.0:*:*:*:*:*:*:*
cpe:2.3:a:haproxy:haproxy:2.7.0:*:*:*:*:*:*:*

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