CVE-2026-66339
Low
No strong exploitation signal.
CVSS base
6.5
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS — probability of exploitation (30 days)
0.2%
13.7th percentile
CISA KEV
Not listed
Weakness / dates
CWE-201
Published 2026-07-24 · modified 2026-08-24
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | R | Required |
| Scope | U | Unchanged |
| Confidentiality | H | High |
| Integrity | N | None |
| Availability | N | None |
Timeline
- 2026-07-24 — Published (NVD)
- 2026-08-24 — Last modified (NVD)
Description
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.