CVE-2026-67354 guzzle CVE debrief

Who should care

Organizations using guzzlehttp/guzzle versions before 7.15.1 should be aware of this high-severity vulnerability and take steps to mitigate it. This includes reviewing and adjusting the allow_redirects.referer setting, monitoring for potential exploitation attempts, and prioritizing upgrades to version 7.15.1 or later. Affected operators, platforms, and security teams should review the vulnerability's impact and implement necessary defensive measures to prevent potential information disclosure via the Referer header. Vulnerability management and security teams should also track exceptions, retest remediated assets, and ensure evidence is documented before closing the item. Compensating controls for exposed systems should be reviewed while remediation is scheduled and verified. Relevant monitoring, detection, and logs for exposed assets should be checked for extra review. Asset inventory and rollback/change windows should also be considered for affected systems. Source tracking and exposure review are crucial in addressing this vulnerability effectively. The vulnerability's severity and potential impact necessitate prompt action from affected organizations to prevent potential security breaches. Security teams should confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. Official advisories or CVE records should be reviewed to validate affected scope, severity, and vendor guidance. Vendor-supported updates or mitigations should be planned through normal change control where exposure is confirmed. The CVE record indicates a high-severity information disclosure vulnerability in guzzlehttp/guzzle versions before 7.15.1, emphasizing the need for immediate attention and remediation. The vulnerability's details and potential impact highlight the importance of implementing defensive measures to protect sensitive client data. By prioritizing upgrades, reviewing settings, and implementing compensating controls, organizations can mitigate the risk associated with this vulnerability and prevent potential security breaches. The CVE-2026-67354 vulnerability underscores the need for proactive vulnerability management and a

Technical summary

The CVE-2026-67354 vulnerability affects guzzlehttp/guzzle versions before 7.15.1. It is related to the RedirectMiddleware and the optional allow_redirects.referer setting. When this setting is enabled, the middleware copies the URI fragment from the referring request into the generated Referer header when following a same-scheme redirect. This can lead to the disclosure of sensitive client data to unintended servers. The vulnerability is fixed in version 7.15.1.

Defensive priority

Organizations using guzzlehttp/guzzle versions before 7.15.1 should prioritize upgrading to 7.15.1 or later to prevent potential information disclosure via the Referer header.

Recommended defensive actions

• Upgrade to guzzlehttp/guzzle version 7.15.1 or later
• Review and adjust the allow_redirects.referer setting
• Monitor for potential exploitation attempts
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE-2026-67354 record indicates a high-severity information disclosure vulnerability in guzzlehttp/guzzle versions before 7.15.1. The vulnerability is related to the RedirectMiddleware and the optional allow_redirects.referer setting. When enabled, this setting can lead to the disclosure of sensitive client data, such as one-time login secrets or access tokens, to unintended servers. The vulnerability is fixed in version 7.15.1, which removes the URI fragment before generating the Referer value.

Official resources