What’s Vulnerable › Vulnerabilities

CVE-2026-73564: frp: Unauthenticated Remote Denial of Service in the frp SSH Tunnel Gateway via Integer Overflow

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-13 · updated 2026-10-24
• Weakness: CWE-129

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: from 0.53.0, < 0.70.1

References

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

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