csirt@kutim:~/threat-intel/cve/CVE-2026-27840

Katalog CVE

CVSS 4.3 · Medium EPSS 0,23%

Kerentanan Authentication Bypass by Assumed-Immutable Data pada zitadel. Skor CVSS 3.1 4.3 (Medium) menurut github.com.

Deskripsi (NVD)

ZITADEL is an open source identity management platform. Starting in version 2.31.0 and prior to versions 3.4.7 and 4.11.0, opaque OIDC access tokens in the v2 format truncated to 80 characters are still considered valid. Zitadel uses a symmetric AES encryption for opaque tokens. The cleartext payload is a concatenation of a couple of identifiers, such as a token ID and user ID. Internally Zitadel has 2 different versions of token payloads. v1 tokens are no longer created, but are still verified as to not invalidate existing session after upgrade. The cleartext payload has a format of `<token_id>:<user_id>`. v2 tokens distinguished further where the `token_id` is of the format `v2_<oidc_session_id>-at_<access_token_id>`. V1 token authZ/N session data is retrieved from the database using the (simple) `token_id` value and `user_id` value. The `user_id` (called `subject` in some parts of our code) was used as being the trusted user ID. V2 token authZ/N session data is retrieved from the database using the `oidc_session_id` and `access_token_id` and in this case the `user_id` from the token is ignored and taken from the session data in the database. By truncating the token to 80 chars, the user_id is now missing from the cleartext of the v2 token. The back-end still accepts this for above reasons. This issue is not considered exploitable, but may look awkward when reproduced. The patch in versions 4.11.0 and 3.4.7 resolves the issue by verifying the `user_id` from the token against the session data from the database. No known workarounds are available.

Rincian

Terbit di NVD
26 Februari 2026
Terakhir diubah
17 Juni 2026
Status NVD
Analyzed
CVSS 3.1
4.3 (Medium), sumber github.com
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N · uraikan di kalkulator
Jenis kelemahan (CWE)
CWE-302: Authentication Bypass by Assumed-Immutable Data
EPSS (30 hari)
0,23% peluang dieksploitasi; lebih tinggi dari 12,6% CVE lain

Produk dan versi terdampak

VendorProdukVersi terdampak
zitadel zitadel Versi 2.31.0 hingga 2.71.19
zitadel zitadel Versi 3.0.0 hingga sebelum 3.4.7
zitadel zitadel Versi 4.0.0 hingga sebelum 4.11.0

> Data dari konfigurasi CPE di NVD.

Referensi dan perbaikan

Sumber: NVD · CVE.org · EPSS. Halaman ini disusun otomatis dari data tersebut; pembaruan terakhir 5 Okt 2026, 20:11 WITA. Kalau sistem di Perangkat Daerah memakai produk ini dan butuh bantuan, laporkan lewat kanal pelaporan.