# CVE-2026-73564

## Summary

- **CVE ID:** CVE-2026-73564
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-129, CWE-190
- **Published:** Aug 13, 2026
- **Last Modified:** Aug 13, 2026

## Description

frp is a fast reverse proxy. From 0.53.0 until 0.70.1, frp's optional SSH Tunnel Gateway in pkg/ssh/server.go parses an SSH exec channel request by adding 4 to an attacker-controlled four-byte big-endian length. A length of 0xFFFFFFFF makes the uint32 addition wrap to 3, defeats the payload bounds check, and causes payload[4:3] to panic in TunnelServer.handleNewChannel. When no authorized-keys file is configured, sshConfig.NoClientAuth permits an unauthenticated peer to reach this channel phase before the frp token is checked, so a single five-byte request terminates the frps process and drops every active tunnel. This issue is fixed in version 0.70.1.

## Affected Products

- fatedier — frp (>= 0.53.0, < 0.70.1)

## References

- [CNA](https://github.com/fatedier/frp/security/advisories/GHSA-26gq-p25f-99cp)
- [CNA](https://github.com/fatedier/frp/pull/5428)
- [CNA](https://github.com/fatedier/frp/commit/7dc7be930e2452ae93fd32f2a77f8c6fcd0b652b)
- [CNA](https://github.com/fatedier/frp/releases/tag/v0.70.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.38%
- **EPSS Percentile:** 31.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._