CVE-2025-59303VulnerabilityPublished 8 Oct 2025

CVE-2025-59303: HAProxy Kubernetes Ingress Controller · Incomplete Filtering of Special Elements

Affects HAProxy Kubernetes Ingress ControllerSource CVE Database V5

Not known to be exploited · CVSS 6.4 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

6.4Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 8 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
HAProxy HAProxy Kubernetes Ingress Controller	Affected =0	Fixed in–

AI-suggested

1. Immediately upgrade to the fixed versions of HAProxy Enterprise Kubernetes Ingress Controller (3.0.16-ee1, 1.11.13-ee1, or 1.9.15-ee1) or later. 2. Disable the config-snippets feature flag if it is not essential to reduce the attack surface. 3. Enforce strict Role-Based Access Control (RBAC) policies to limit create/update permissions on ingress resources to trusted administrators only. 4. Implement monitoring and alerting for unusual ingress configuration changes or suspicious access patterns. 5. Conduct regular audits of ingress resource configurations to detect unauthorized snippets or anomalies. 6. Use network segmentation and Kubernetes network policies to limit exposure of ingress controllers. 7. Educate DevOps and security teams about the risks associated with config-snippets and the importance of least privilege principles. 8. Integrate vulnerability scanning and compliance checks into CI/CD pipelines to catch vulnerable versions before deployment.

Description

HAProxy Kubernetes Ingress Controller before 3.1.13, when the config-snippets feature flag is used, accepts config snippets from users with create/update permissions. This can result in obtaining an ingress token secret as a response. The fixed versions of HAProxy Enterprise Kubernetes Ingress Controller are 3.0.16-ee1, 1.11.13-ee1, and 1.9.15-ee1.

Impact

For European organizations, this vulnerability poses a significant risk to Kubernetes cluster security, particularly those relying on HAProxy Kubernetes Ingress Controller for ingress management. Exposure of ingress token secrets can lead to unauthorized access to cluster resources, potentially allowing attackers to manipulate ingress traffic, intercept sensitive data, or escalate privileges within the cluster. This can disrupt business operations, compromise data confidentiality, and violate compliance requirements such as GDPR. Organizations with multi-tenant or hybrid cloud environments are especially vulnerable due to the potential lateral movement within clusters. The impact is heightened in sectors with critical infrastructure or sensitive data, including finance, healthcare, and government institutions. Given the widespread adoption of Kubernetes and HAProxy in Europe, failure to address this vulnerability could result in targeted attacks exploiting this vector to gain footholds in enterprise cloud environments.

CWE-791Incomplete Filtering of Special Elements (opens in a new tab)
Base weakness
The product receives data from an upstream component, but does not completely filter special elements before sending it to a downstream component.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
V5.2.2 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

haproxy.com/blog/cve-2025-59303-haproxy-kubernetes-ingress-controller-secret-leak (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 8 Oct 2025, 16:29 UTC

WeaknessesCWE-791

Technical details

References

Community reviews

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