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High, CVSS 8.2amended

frp: Unauthenticated Remote Denial of Service in the frp SSH Tunnel Gateway via Integer Overflow

CVE-2026-73564GHSA-26gq-p25f-99cp

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/fatedier/frp 0.70.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-73564: 0.52% estimated exploitation activity in the next 30 days; percentile 44.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary An integer-overflow vulnerability in the frp server's optional SSH Tunnel Gateway lets any unauthenticated remote attacker crash the entire frps process with a single five-byte message. When the gateway parses an SSH exec channel request in pkg/ssh/server.go, it adds a small constant to a four-byte length value taken directly from the request. Because that length is fully attacker-controlled, a value of 0xFFFFFFFF makes the addition wrap around to a tiny number, defeating the only bounds check and forcing an out-of-range slice. Go raises a panic that nothing recovers, so the whole server exits. In the default gateway mode SSH clients are not authenticated and the request is handled before any frp token is checked, so the crash is reachable pre-authentication. It carries no state and is trivially repeatable, turning one crash into a sustained outage that drops every tunnel for every user. Details The exec request payload is a four-byte big-endian length followed by that many…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-26gq-p25f-99cp

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GO-2026-6103

Agent brief

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# Patch Next advisory brief: CVE-2026-73564

Advisory: frp: Unauthenticated Remote Denial of Service in the frp SSH Tunnel Gateway via Integer Overflow
IDs: CVE-2026-73564, GHSA-26gq-p25f-99cp
Record: https://patchnext.com/advisories/cve-2026-73564 (revision 3, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/fatedier/frp 0.70.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/fatedier/frp: affected >= 0.53.0, <= 0.70.0; fixed in 0.70.1

## Suggested inspection (read-only)
- Go github.com/fatedier/frp: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/fatedier/frp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6103 (OSV record GO-2026-6103 lists affected ranges: Go github.com/fatedier/frp >=0.53.0 <0.70.1 (fixed))
- Verified: https://github.com/advisories/GHSA-26gq-p25f-99cp (GitHub-reviewed advisory GHSA-26gq-p25f-99cp lists affected ranges: Go github.com/fatedier/frp >=0.53.0 <=0.70.0)

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