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CVE-2026-6253

5.9 · MEDIUM

curl might erroneously pass on credentials for a first proxy to a second proxy.

Published May 13, 2026CWE-522EPSS 0.72%

Overview

CVE-2026-6253 is a medium-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

curl might erroneously pass on credentials for a first proxy to a second

proxy.

This can happen when the following conditions are true:

1. curl is setup to use specific different proxies for different URL schemes

2. the first proxy needs credentials

3. the second proxy uses no credentials

4. while using the first proxy (using say `http://`), curl is asked to follow

a redirect to a URL using another scheme (say `https://`), accessed using a

second, different, proxy

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refcurl.se/docs/CVE-2026-6253.htmlRefcurl.se/docs/CVE-2026-6253.jsonRefhackerone.com/reports/3669637Refwww.openwall.com/lists/oss-security/2026/04/29/11Refhackerone.com/reports/3669637

How CyberStrike helps

Frequently asked questions

What is CVE-2026-6253?

CVE-2026-6253 is a medium-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-6253?

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-6253?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-6253?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-6253 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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