Project Subscriptions
No data.
No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Wed, 26 Aug 2026 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Wed, 26 Aug 2026 10:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | mcp-fetch checks a fetch target against its SSRF guard without removing the brackets that surround an IPv6 literal. isSafeUrl reads the hostname from the parsed URL, which for a literal such as http://[::1]/ yields the bracketed string, and then tests it with net.isIP. That call returns zero for a bracketed value, so the branch holding the private-address checks is skipped entirely. The guard falls back to resolving the hostname, the bracketed string is not a resolvable name, no addresses are returned, and the target is reported safe. The HTTP client then strips the brackets and connects. Because the address may be given in IPv4-mapped form, the same path reaches any IPv4 target the loopback and private checks were meant to exclude, including link-local metadata endpoints. isPrivateIPv6 also has no case for the ::ffff: prefix, so the mapped form would still pass even if the brackets were removed. The fetch target is supplied as a tool argument, so an attacker who can influence what the model requests can read internal responses back into the model context. | |
| Title | mcp-fetch through 1.6.3 Server-Side Request Forgery via Unstripped IPv6 Literal Brackets | |
| Weaknesses | CWE-918 | |
| References |
| |
| Metrics |
cvssV3_1
|
Projects
Sign in to view the affected projects.
Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-08-26T12:05:24.996Z
Reserved: 2026-08-26T09:56:49.602Z
Link: CVE-2026-80347
Updated: 2026-08-26T12:05:12.020Z
Status : Received
Published: 2026-08-26T10:16:42.803
Modified: 2026-08-26T13:19:24.960
Link: CVE-2026-80347
No data.
OpenCVE Enrichment
Updated: 2026-08-26T11:30:05Z