High 7.1Published Sep 28, 2026

CVE-2026-55096SSRF via DNS-resolution gap in _validate_url_security (file download by URL)

Updated under an hour ago (2026-10-19 09:40 UTC)

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It affects leshchenko1979 fast-mcp-telegram. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.21%, higher than 10% of scored CVEs.

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Every CVE for leshchenko1979 fast-mcp-telegram

Exploited in the last 30 days

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.

CVSS: 7.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness (CWE): CWE-184, CWE-918
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.21% (percentile 10)
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 1, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

leshchenko1979 fast-mcp-telegram leshchenko1979:fast_mcp_telegram (from the name)	before 30.1	CNA record

References

https://github.com/leshchenko1979/fast-mcp-telegram/security/advisories/GHSA-xr72-j7vj-vp7gx-refsource-confirm
https://github.com/leshchenko1979/fast-mcp-telegram/commit/e6b3032cfc906e14f5b84f2c2b8ec378eb457e57x-refsource-misc
https://github.com/leshchenko1979/fast-mcp-telegram/releases/tag/0.30.1x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.