Chisel has an ACL Bypass via Post-Handshake SSH Channel ExtraData Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.5 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:H/SA:L · score source

EPSS

• CVE-2026-48113: 0.39% estimated exploitation activity in the next 30 days; percentile 32.81 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Authenticated chisel clients can bypass --authfile ACL restrictions and tunnel traffic to arbitrary destinations reachable from the server. The ACL is enforced only during the initial handshake against declared remotes, but never on subsequent SSH channels that carry actual traffic. A malicious client authenticates with a permitted remote, then opens channels to any host:port it wants. Details The chisel server validates user ACLs in two places but is missing validation in one of the important places. The server/serverhandler.go checks the ACL, during the initial config handshake: This validates the declared remote list from the client's config request. It runs once, at connection setup. But in share/tunnel/tunneloutssh.go ACL aren't being checked, when the server processes actual traffic channels: The tunnel.Config struct has no User field, no allowed-address list, and no ACL callback. The user context from serverhandler.go is never propagated to the tunnel layer: Since…

Published by the source

12 Jun 2026, 15:04 UTC

Last modified by the source

12 Jun 2026, 15:04 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-24fp-5v3p-rvpw

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# Patch Next advisory brief: CVE-2026-48113

Advisory: Chisel has an ACL Bypass via Post-Handshake SSH Channel ExtraData Injection
IDs: CVE-2026-48113, GHSA-24fp-5v3p-rvpw
Record: https://patchnext.com/advisories/cve-2026-48113 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/jpillora/chisel 1.11.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/jpillora/chisel: affected <= 1.11.4; fixed in 1.11.5

## Suggested inspection (read-only)
- Go github.com/jpillora/chisel: 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/jpillora/chisel.
- 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://github.com/advisories/GHSA-24fp-5v3p-rvpw (GitHub-reviewed advisory GHSA-24fp-5v3p-rvpw lists affected ranges: Go github.com/jpillora/chisel >=0 <=1.11.4)

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