fatedier frp up to 0.70.0 SSH Tunnel Gateway pkg/ssh/server.go TunnelServer.handleNewChannel integer overflow

Summaryinfo

A vulnerability marked as problematic has been reported in fatedier frp up to 0.70.0. Affected is the function TunnelServer.handleNewChannel of the file pkg/ssh/server.go of the component SSH Tunnel Gateway. The manipulation leads to integer overflow. This vulnerability is traded as CVE-2026-73564. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in fatedier frp up to 0.70.0. This issue affects the function TunnelServer.handleNewChannel of the file pkg/ssh/server.go of the component SSH Tunnel Gateway. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-73564 since 08/12/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 0.70.1 eliminates this vulnerability.

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Productinfo

Vendor

• fatedier

Name

• frp

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31
• 0.32
• 0.33
• 0.34
• 0.35
• 0.36
• 0.37
• 0.38
• 0.39
• 0.40
• 0.41
• 0.42
• 0.43
• 0.44
• 0.45
• 0.46
• 0.47
• 0.48
• 0.49
• 0.50
• 0.51
• 0.52
• 0.53
• 0.54
• 0.55
• 0.56
• 0.57
• 0.58
• 0.59
• 0.60
• 0.61
• 0.62
• 0.63
• 0.64
• 0.65
• 0.66
• 0.67
• 0.68
• 0.69
• 0.70.0

Website

• Product: https://github.com/fatedier/frp/

CPE 2.3info

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