Vulnerability details
CVE-2026-73564
frp: Unauthenticated Remote Denial of Service in the frp SSH Tunnel Gateway via Integer Overflow
Official 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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 8.7High | 4.0 | CVEProject cvelistV5 (CNA) (GitHub_M) | 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 |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| fatedier | frp | >= 0.53.0, < 0.70.1 | CVEProject cvelistV5 (CNA) |
References and advisories
4- https://github.com/fatedier/frp/pull/5428 x_refsource_MISC
- https://github.com/fatedier/frp/commit/7dc7be930e2452ae93fd32f2a77f8c6fcd0b652b x_refsource_MISC
- https://github.com/fatedier/frp/releases/tag/v0.70.1 x_refsource_MISC
- https://github.com/fatedier/frp/security/advisories/GHSA-26gq-p25f-99cp x_refsource_CONFIRM
Details
- Published
- 2026-08-13
- Last updated
- 2026-08-13
- State
- Published
- Assigner (CNA)
- GitHub_M
Exploit prediction (EPSS)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- Proof of concept
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-129Improper Validation of Array Index
- CWE-190Integer Overflow or Wraparound