Telepresence: Tunnel endpoint accepts caller-supplied session ID with no ownership proof — active client sessions hijackable
Telepresence versions up to and including 2.28.0 are affected, and the attacker needs a valid active client session ID. The vendor gives no severity rating. Fixed in 2.31.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 2.31.0
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Telepresence versions up to and including v2.28.0 are affected; the fix is in 2.31.0. The attacker needs a valid active session ID of a Telepresence client.
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity8.2/10CVSS 8.2
- No patch0/5No signal
What would change the score
- Would score about 66 if added to CISA KEV
- Would score about 61 if CISA's SSVC rates exploitation active
- Would score about 23 if CISA's SSVC rates it automatable
CVE-2026-102339 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.2 (high) and affects telepresence; fixed in 2.31.0.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 16/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 2.31.0
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Telepresence, a tool for developing locally against remote Kubernetes or OpenShift clusters, lets a remote attacker with a low-privilege account hijack another client's active session and gain its network routing capabilities. The Traffic Manager Tunnel endpoint accepts a caller-supplied session ID without checking that the caller owns the session, so the attacker needs only a valid active session ID, which can leak through logs, cluster-internal channels, or the unauthenticated ArriveAsClient endpoint.
Read the original description
Telepresence enables local development against a remote Kubernetes or OpenShift cluster. Prior to 2.31.0, the Traffic Manager Tunnel gRPC streaming endpoint parses a session ID from the first bytes of a caller-controlled message in pkg/tunnel/message.go and passes it to state.Tunnel without verifying that the caller owns the active session. An attacker who obtains a valid active session ID through log leakage, cluster-internal channels, or the unauthenticated ArriveAsClient endpoint can attach a routed tunnel to that session and gain its network routing capabilities. UUID4 session IDs make cold brute force impractical. This vulnerability is fixed in 2.31.0.
What to do
Check whether your setup matches what the bug needs.
Telepresence versions up to and including v2.28.0 are affected; the fix is in 2.31.0. The attacker needs a valid active session ID of a Telepresence client.Upgrade to a fixed version: 2.31.0.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- telepresenceio telepresence
fixed in 2.31.0
Evidence 5
- Advisory
- Repository
- Repository
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-102339
Is CVE-2026-102339 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The tunnel endpoint accepts a session ID supplied by the caller without checking that the caller owns that session. A caller who holds a valid active session ID of a Telepresence client can therefore use that client's session.Source: github.com, github.com
Which versions are affected by CVE-2026-102339?
telepresence: before 2.31.0.Source: cve.now feed data
Am I affected, and how do I check?
Telepresence versions up to and including v2.28.0 are affected; the advisory tested HEAD v2.28.0 at commit b2231a4. To check a installation, run the telepresence version command and compare the reported version with 2.28.0. The stated precondition is a valid active session ID of a Telepresence client.Source: github.com, github.com
How do I fix CVE-2026-102339?
Upgrade to Telepresence 2.31.0, the fixed release listed in the v2.31.0 release notes.Source: github.com, github.com
Why do the sources disagree?
The description calls the endpoint unauthenticated and says it accepts a session ID with no ownership proof. The CVSS vector instead marks privileges required as low (PR:L), which means some privileges are needed. The sources do not resolve which description fits the vector.Source: github.com, github.com