7.2High
CVE-2026-91143
goproxy through 15.3 fails to apply HTTP proxy basic authentication to CONNECT tunnel requests, allowing unauthenticated clients to bypass credential requirements. Attackers can issue CONNECT requests to establish tunnels through the authenticated proxy without providing credentials, enabling arbitrary TCP traffic relay and access to restricted destinations.
What this means for your business
- An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.3% chance of attack attempts being seen in the next 30 days, ranking above 19% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
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Scoring
- CVSS
- 7.2 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N- CVSS v4
- 6.9
- Weakness
- CWE-288
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-09-14
- Last modified
- 2026-09-15
- Sources
- NVD
References
- https://github.com/geo-chen/oss/blob/main/goproxy.md
- https://github.com/snail007/goproxy
- https://github.com/snail007/goproxy/blob/v15.3/services/http.go
- https://github.com/snail007/goproxy/blob/v15.3/utils/structs.go
- https://www.vulncheck.com/advisories/goproxy-through-15.3-authentication-bypass-via-connect