CVE-2026-55672

ZITADEL is an open source identity management platform. Prior to 3.4.12 and 4.15.2, ZITADEL's OAuth2 and OIDC CodeExchange, RefreshToken, and device token flows fail to verify that the requesting client matches the client that initiated the authorization flow, allowing intercepted grants or refresh tokens to be exchanged under a different client. This issue is fixed in versions 3.4.12 and 4.15.2.

ZITADEL is an open source identity management platform. Prior to 3.4.12 and 4.15.2, ZITADEL's OAuth2 and OIDC CodeExchange, RefreshToken, and device token flows fail to verify that the requesting client matches the client that initiated the authorization flow, allowing intercepted grants or refresh tokens to be exchanged under a different client. This issue is fixed in versions 3.4.12 and 4.15.2.

Summary

Zitadel's OAuth2 / OIDC CodeExchange and RefreshToken implementations omit a critical validation step to ensure that the requesting client matches the client that originally initiated the authorization flow. This violates RFC 6749 Section 4.1.3, which mandates that the authorization server must ensure the authorization code was issued to the authenticated confidential client.

Impact

This flaw creates potential vulnerabilities in two main authentication phases, provided specific external preconditions are met:

• Authorization Code Injection: An attacker who intercepts an authorization code (via an independent application vulnerability such as XSS, referrer leakage, log access, or network interception) can exchange it using credentials from a completely different client (ClientB) registered on the same Zitadel instance. Zitadel will authenticate ClientB and issue tokens for the victim user without verifying the client binding.
• Refresh Token Cross-Use: An attacker who successfully steals a valid refresh token (via an external application exploit or data leak) can present it under a different client identity. Zitadel validates the token's format and expiration but fails to enforce client binding, allowing the attacker to maintain persistent access from an unauthorized client.
• Device Authorization Cross-Use: An attacker who intercepts or manipulates a device authorization flow grant can finalize the exchange using a different client context than the one that initiated the device session, bypassing intended client boundaries.

Scope and Mitigation Factors:

• External Preconditions: It is critical to note that exploiting either vector requires a pre-existing vulnerability or data leak within the target application environment to intercept the code or token in the first place. Securing the application layer against token theft remains outside the scope of Zitadel.
• Multi-tenant risk: On shared or multi-tenant instances, a client belonging to one tenant could theoretically exploit codes/tokens belonging to another tenant's clients if they are successfully intercepted.
• PKCE protection: Clients strictly using PKCE (Proof Key for Code Exchange) are partially mitigated against the authorization code injection vector, as the attacker would still require the code_verifier. However, PKCE does not protect against refresh token cross-use.

Affected Versions

Systems running one of the following versions are affected:

• 4.x: 4.0.0 through 4.15.1 (including RC versions)
• 3.x: 3.0.0 through 3.4.11 (including RC versions)

Patches

The vulnerability has been addressed in the latest releases by re-introducing strict client identity validation on the CodeExchange and RefreshToken grants.

Please upgrade to one of the following secure versions:

• 4.x: Upgrade to $\ge$4.15.2
• 3.x: Update to $\ge$3.4.12

Workarounds

The recommended solution is to upgrade to a patched version.

To reduce exposure in the interim, ensure absolute adherence to application security best practices to prevent credential/token theft, enforce the use of PKCE for all clients to mitigate the Authorization Code Injection risk, and minimize refresh token lifespans.

Questions

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

Credits

Thanks to kodareef5, Shubham Raj / Causal Security, and Gaurav Popalghat for identifying and responsibly reporting this or a part of this vulnerability.

ZITADEL is an open source identity management platform. Prior to 3.4.12 and 4.15.2, ZITADEL's OAuth2 and OIDC CodeExchange, RefreshToken, and device token flows fail to verify that the requesting client matches the client that initiated the authorization flow, allowing intercepted grants or refresh tokens to be exchanged under a different client. This issue is fixed in versions 3.4.12 and 4.15.2.

ZITADEL is an open source identity management platform. Prior to 3.4.12 and 4.15.2, ZITADEL's OAuth2 and OIDC CodeExchange, RefreshToken, and device token flows fail to verify that the requesting client matches the client that initiated the authorization flow, allowing intercepted grants or refresh tokens to be exchanged under a different client. This issue is fixed in versions 3.4.12 and 4.15.2.

Summary

Zitadel's OAuth2 / OIDC CodeExchange and RefreshToken implementations omit a critical validation step to ensure that the requesting client matches the client that originally initiated the authorization flow. This violates RFC 6749 Section 4.1.3, which mandates that the authorization server must ensure the authorization code was issued to the authenticated confidential client.

Impact

This flaw creates potential vulnerabilities in two main authentication phases, provided specific external preconditions are met:

• Authorization Code Injection: An attacker who intercepts an authorization code (via an independent application vulnerability such as XSS, referrer leakage, log access, or network interception) can exchange it using credentials from a completely different client (ClientB) registered on the same Zitadel instance. Zitadel will authenticate ClientB and issue tokens for the victim user without verifying the client binding.
• Refresh Token Cross-Use: An attacker who successfully steals a valid refresh token (via an external application exploit or data leak) can present it under a different client identity. Zitadel validates the token's format and expiration but fails to enforce client binding, allowing the attacker to maintain persistent access from an unauthorized client.
• Device Authorization Cross-Use: An attacker who intercepts or manipulates a device authorization flow grant can finalize the exchange using a different client context than the one that initiated the device session, bypassing intended client boundaries.

Scope and Mitigation Factors:

• External Preconditions: It is critical to note that exploiting either vector requires a pre-existing vulnerability or data leak within the target application environment to intercept the code or token in the first place. Securing the application layer against token theft remains outside the scope of Zitadel.
• Multi-tenant risk: On shared or multi-tenant instances, a client belonging to one tenant could theoretically exploit codes/tokens belonging to another tenant's clients if they are successfully intercepted.
• PKCE protection: Clients strictly using PKCE (Proof Key for Code Exchange) are partially mitigated against the authorization code injection vector, as the attacker would still require the code_verifier. However, PKCE does not protect against refresh token cross-use.

Affected Versions

Systems running one of the following versions are affected:

• 4.x: 4.0.0 through 4.15.1 (including RC versions)
• 3.x: 3.0.0 through 3.4.11 (including RC versions)

Patches

The vulnerability has been addressed in the latest releases by re-introducing strict client identity validation on the CodeExchange and RefreshToken grants.

Please upgrade to one of the following secure versions:

• 4.x: Upgrade to $\ge$4.15.2
• 3.x: Update to $\ge$3.4.12

Workarounds

The recommended solution is to upgrade to a patched version.

To reduce exposure in the interim, ensure absolute adherence to application security best practices to prevent credential/token theft, enforce the use of PKCE for all clients to mitigate the Authorization Code Injection risk, and minimize refresh token lifespans.

Questions

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

Credits

Thanks to kodareef5, Shubham Raj / Causal Security, and Gaurav Popalghat for identifying and responsibly reporting this or a part of this vulnerability.

ZITADEL: Missing client_id binding in OIDC authorization code exchange and refresh token flows (RFC 6749 Section 4.1.3 violation) in github.com/zitadel/zitadel

This update for govulncheck-vulndb fixes the following issues:

• Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

• GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
• GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
• GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
• GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
• GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
• GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
• GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
• GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
• GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
• GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
• GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
• GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
• GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
• GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
• GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
• GO-2026-5933 GHSA-3g4q-2f67-2gvh
• GO-2026-5934 GHSA-59qp-cfj3-rp64
• GO-2026-5935 GHSA-7856-g3gv-9wq8
• GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
• GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
• GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
• GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
• GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
• GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
• GO-2026-5942 CVE-2026-46600
• GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
• GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
• GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
• GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
• GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
• GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
• GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
• GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
• GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
• GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
• GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
• GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
• GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
• GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
• GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
• GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
• GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
• GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
• GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
• GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
• GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
• GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
• GO-2026-5969 GHSA-g936-7jqj-mwv8
• GO-2026-5970 CVE-2026-56852
• GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
• GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
• GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
• GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
• GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
• GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
• GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
• GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
• GO-2026-5981 GHSA-mqxv-9rm6-w8qc
• GO-2026-5982 GHSA-pqg7-v6wh-3pfp
• GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
• GO-2026-5985 GHSA-7rx3-5wx3-5v76
• GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
• GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
• GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
• GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
• GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
• GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
• GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
• GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
• GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
• GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
• GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
• GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
• GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
• GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
• GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
• GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…