CVE-2026-73564 - frp: Unauthenticated Remote Denial of Service in the frp SSH Tunnel Gateway via Integer Overflow
CVE ID :CVE-2026-73564
Published : Aug. 13, 2026, 6:18 p.m. | 1 hour, 10 minutes ago
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.
Severity: 8.7 | HIGH
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Published : Aug. 13, 2026, 6:18 p.m. | 1 hour, 10 minutes ago
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.
Severity: 8.7 | HIGH
Visit the link for more details, such as CVSS details, affected products, timeline, and more...