PatchSiren cyber security CVE debrief
CVE-2026-67339 guzzle CVE debrief
AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-08-01T13:17:04.990Z and has not been modified since then. Guzzle HTTP client library versions before 7.14.2 fail to properly isolate Proxy-Authorization headers from origin servers in cURL handlers. This vulnerability potentially exposes proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies misclassified as direct connections. The issue requires immediate attention due to the potential for proxy credential exposure. Developers and administrators using Guzzle HTTP client library, especially those handling sensitive proxy credentials or using SOCKS proxies, should take action. Limited evidence is available, primarily based on official records from CVE.org and NVD. Defenders should verify Guzzle library usage, review proxy configurations, and monitor for suspicious proxy authentication attempts.
- Vendor
- guzzle
- Product
- Unknown
- CVSS
- MEDIUM 6.9
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-08-01
- Original CVE updated
- 2026-08-01
- Advisory published
- 2026-08-01
- Advisory updated
- 2026-08-01
Who should care
Developers and administrators using Guzzle HTTP client library, especially those handling sensitive proxy credentials or using SOCKS proxies, should take immediate action to address this vulnerability. This includes verifying Guzzle library usage, applying vendor patches or upgrades, and reviewing proxy configurations. Security teams and vulnerability management teams should also prioritize this issue due to its potential impact on proxy credential security.
Technical summary
Guzzle HTTP client library versions before 7.14.2 fail to properly isolate Proxy-Authorization headers from origin servers in cURL handlers. This vulnerability potentially exposes proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies misclassified as direct connections. The issue requires immediate attention due to the potential for proxy credential exposure. Developers and administrators using Guzzle HTTP client library, especially those handling sensitive proxy credentials or using SOCKS proxies, should take action.
Defensive priority
Medium-severity vulnerability in Guzzle HTTP client library requires immediate attention due to potential for proxy credential exposure.
Recommended defensive actions
- Inventory Guzzle library usage and verify version
- Apply vendor patch or upgrade to version 7.14.2 or later
- Monitor for suspicious proxy authentication attempts
- Review and update SOCKS proxy configurations
- Implement additional logging and monitoring for proxy requests
- Review compensating controls for exposed systems while remediation is scheduled and verified
- Track exceptions, retest remediated assets, and close the item only after evidence is documented
Evidence notes
The evidence for this CVE is limited, primarily based on official records from CVE.org and NVD. The Guzzle HTTP client library vulnerability (CVE-2026-67339) allows attackers to capture proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies that Guzzle misclassifies as direct connections. Defenders should verify Guzzle library usage, review proxy configurations, and monitor for suspicious proxy authentication attempts. Additional verification tasks include reviewing compensating controls for exposed systems and tracking exceptions.
Official resources
AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-08-01T13:17:04.990Z and has not been modified since then.