CVE-2026-66339

mediumCVSS 6.5covered by 1 sourcefirst seen 2026-07-24

A flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libsoup incorrectly attaches the Proxy-Authorization header to subsequent HTTPS requests sent through that tunnel to the destination server. This allows the destination server to capture proxy credentials, leading to information disclosure.

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Exploitation outlook

Low exploitation risk0.23% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 14% of all EPSS-scored CVEs.

Advisory coverage (1)

mediumCVE-2026-66339: A flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libs…nvd · 2026-07-24

External references

NVD record for CVE-2026-66339

CVE.org record

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