How severe is CVE-2026-56668?

CVE-2026-56668 has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-56668?

CVE-2026-56668 affects the following packages: github.com/zitadel/zitadel (Go). Ecosystems affected: Go.

How do I fix CVE-2026-56668?

Update github.com/zitadel/zitadel to 4.15.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56668 is resolved across your whole dependency graph.

How do I detect CVE-2026-56668 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-56668 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-56668 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-56668 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-56668?

CVE-2026-56668 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 35th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-56668?

CVE-2026-56668 is classified as CWE-862 (CWE-862). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-56668 published, and has it been updated?

CVE-2026-56668 was published on July 10, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2026-56668 — zitadel

HIGHFix: zitadel/zitadel@e2886a6

CVE-2026-56668 is a high-severity (CVSS 8.1) CWE-862 vulnerability in github.com/zitadel/zitadel. A fix is available for github.com/zitadel/zitadel — see the affected versions and patch details below.

ZITADEL: Unauthorized Token Privilege Escalation in OAuth2 Token Exchange

Also known asGHSA-vrh8-c9cm-wh8vGO-2026-6474

Published

Jul 10, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-56668.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs35th percentile — riskier than 35% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-56668 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 397,508 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐹github.com/zitadel/zitadel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

A vulnerability in ZITADEL’s OAuth2 Token Exchange endpoint allows an authenticated user or client to exchange a low-privilege access token for a token with elevated permissions at a completely different application. This bypasses the intended authorization and separation policies configured within ZITADEL.

Impact

ZITADEL enables administrators to restrict token issuance based on client permissions, project roles, and specific scopes. Due to a missing verification step during the Token Exchange flow (urn:ietf:params:oauth:grant-type:token-exchange), ZITADEL fails to validate whether the incoming access token belongs to or is authorized for the client initiating the exchange. Additionally, ZITADEL does not enforce that the newly requested scopes must stay within the boundaries of the original token's scopes.

An attacker with valid access to a low-privilege application can exploit this behavior by sending a token exchange request to a highly-privileged target application. This allows them to obtain administrative project roles, access sensitive profile data, or gain unauthorized access to other applications across the system. If public clients (which do not require client secrets) are used, this risk increases significantly as it requires no client authentication.

Affected Versions

Systems running one of the following versions are affected:

4.x: 4.0.0 through 4.15.2 (including RC versions)
3.x: 3.0.0 through 3.4.12 (including RC versions)

Patches

The vulnerability has been addressed in the latest releases. The patch resolves the issue by enforcing strict audience ownership verification and ensuring that requested scopes during a token exchange are restricted to a subset of the original token’s scopes.

4.x: Upgrade to $\ge$ 4.15.3
3.x: Upgrade to $\ge$ 4.15.3

Workarounds

The recommended solution is to upgrade to a patched version immediately. If an immediate upgrade is not possible, implement one of the following mitigations:

Disable via Feature Flag: Ensure the Token Exchange feature flag is explicitly turned off in your instance settings or environment variables (ZITADEL_DEFAULTINSTANCE_FEATURES_TOKENEXCHANGE=false). If the feature flag is disabled, the endpoint is unreachable and your system is not vulnerable. This is only possible in versions prior to v4.11.0, where the feature was not yet GA.
Remove the Grant Type: Ensure that the Token Exchange grant type is completely disabled or removed from all configured applications—especially high-privilege or public clients.

Questions

If you have any questions or comments about this advisory, please email us at [email protected].

Credits

Thanks to thesecguy45 and Shubham Raj / Causal Security for reporting this vulnerability.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/zitadel/zitadel`	all versions	4.15.3`go get github.com/zitadel/zitadel@v4.15.3`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/zitadel/zitadel to 4.15.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56668 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Summary A vulnerability in ZITADEL’s OAuth2 Token Exchange endpoint allows an authenticated user or client to exchange a low-privilege access token for a token with elevated permissions at a completely different application. This bypasses the intended authorization and separation policies configured within ZITADEL. ### Impact ZITADEL enables administrators to restrict token issuance based on client permissions, project roles, and specific scopes. Due to a missing verification step during the Token Exchange flow (`urn:ietf:params:oauth:grant-type:token-exchange`), ZITADEL fails to valida