All vulnerabilities
CVE-2026-55096GHSA-xr72-j7vj-vp7g

fast-mcp-telegram: SSRF via DNS-resolution gap in _validate_url_security (file download by URL)

leshchenko1979 fast-mcp-telegram
Open in ThreatlineRecord JSON
CVSS
7.1High
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 1 Oct 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.21%Chance of exploitation activity in the next 30 days, higher than 9% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published28 Sep 2026Updated 1 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Description

fast-mcp-telegram is a Telegram MCP Server. Prior to version 30.1, the send_message/send_message_to_phone MCP tools accept files as a list of http(s) URLs, which the server downloads and attaches to the outgoing Telegram message. Downloads are guarded by _validate_url_security, an SSRF denylist that checks the URL's literal hostname string but never resolves DNS. The fetch (httpx.AsyncClient.get) does its own resolution at request time. Consequently a hostname that resolves to a loopback / private / link-local address passes the guard and is fetched — even with the secure defaults block_private_ips=True and allow_http_urls=False. Because the fetched body is returned to the attacker as a Telegram file attachment, this is a full-read, exfiltrating SSRF, not blind. This issue has been patched in version 30.1.

Text from CVE List

Affected versions 1

  • fast-mcp-telegramaffected: < 30.1CVE List

References 3