Telepresence: Tunnel endpoint accepts caller-supplied session ID with no ownership proof — active client sessions hijackable

Exploitation

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

CVSS

8.2 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-102339: 0.29% estimated exploitation activity in the next 30 days; percentile 21.40 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Traffic Manager `Tunnel` gRPC streaming endpoint accepts a session ID from the first bytes of the client-controlled message payload. No verification confirms the caller owns the session. An attacker supplying a valid active session ID receives a fully routed tunnel for that session, gaining the network routing capabilities of the legitimate Telepresence client. Tested on HEAD v2.28.0, commit b2231a4.

Details The `Tunnel` handler reads identity from a client-provided binary payload rather than from a verified credential or prior authenticated gRPC call: ```go // cmd/traffic/cmd/manager/service.go:1057-1063 func (s *service) Tunnel(server grpc.BidiStreamingServer[...]) error { stream, err := tunnel.NewServerStream(ctx, tunnel.ClientToManager, server) return s.state.Tunnel(ctx, stream) // stream.SessionID() is client-controlled } ``` `state.Tunnel` looks up the session ID in the sessions map with no ownership proof: ```go //…

Published by the source

9 Nov 2026, 21:58 UTC

Last modified by the source

9 Nov 2026, 22:15 UTC

Source last checked

10 Nov 2026, 06:45 UTC

1. Revision 2 · amended · 10 Nov 2026

   Amended from osv record GHSA-6j3h-rp73-6rvf

2. Revision 1 · created · 9 Nov 2026

   Published from ghsa record GHSA-6j3h-rp73-6rvf

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# Patch Next advisory brief: CVE-2026-102339

Advisory: Telepresence: Tunnel endpoint accepts caller-supplied session ID with no ownership proof — active client sessions hijackable
IDs: CVE-2026-102339, GHSA-6j3h-rp73-6rvf
Record: https://patchnext.com/advisories/cve-2026-102339 (revision 2, source checked 10 Nov 2026, 06:45 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/telepresenceio/telepresence/v2 2.31.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/telepresenceio/telepresence/v2: affected < 2.31.0; fixed in 2.31.0

## Suggested inspection (read-only)
- Go github.com/telepresenceio/telepresence/v2: 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/telepresenceio/telepresence/v2.
- 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-6j3h-rp73-6rvf (GitHub-reviewed advisory GHSA-6j3h-rp73-6rvf lists affected ranges: Go github.com/telepresenceio/telepresence/v2 >=0 <2.31.0)
- Verified: https://osv.dev/vulnerability/GHSA-6j3h-rp73-6rvf (OSV record GHSA-6j3h-rp73-6rvf lists affected ranges: Go github.com/telepresenceio/telepresence/v2 >=0 <2.31.0 (fixed))

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