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NVD / CVE Program· CNA GitHub_M

CVE-2026-27840: ZITADEL's truncated opaque tokens are still valid

Noroxi assessment

Priority: Monitor (action score 17/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.15% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: github.com/zitadel/zitadel (Go) 3.4.7, 4.11.0, 1.80.0-v2.20.0.20260216092519-feab8e1fa371.

Low priority for now. Upgrade to github.com/zitadel/zitadel (Go) 3.4.7, 4.11.0, 1.80.0-v2.20.0.20260216092519-feab8e1fa371 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Feb 25, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 5th percentile

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
zitadelzitadel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • zitadel zitadel2.31.0 and later · up to 2.71.19 inclusive
  • zitadel zitadel3.0.0 and later · before 3.4.7
  • zitadel zitadel4.0.0 and later · before 4.11.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • zitadel zitadel

    • >= 4.0.0, < 4.11.0, >= 3.0.0, < 3.4.7, >= 2.31.0, <= 2.71.19affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Gogithub.com/zitadel/zitadelfrom 0—
Gogithub.com/zitadel/zitadelfrom 2.31.0 · up to and including 2.71.19—
Gogithub.com/zitadel/zitadelfrom 3.0.0 · before 3.4.73.4.7
Gogithub.com/zitadel/zitadelfrom 4.0.0 · before 4.11.04.11.0
Gogithub.com/zitadel/zitadelbefore 1.80.0-v2.20.0.20260216092519-feab8e1fa3711.80.0-v2.20.0.20260216092519-feab8e1fa371

Same product

zitadel: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-109372ZITADEL 3.0.0 before 4.19.2 Account Takeover via SAML Identity-Provider Confusion
    37Monitor
  • CVE-2026-105215ZITADEL before 4.16.2 Account Pre-Hijacking via Forged External IdP Callback
    37Monitor
  • CVE-2026-105209ZITADEL before 3.4.15 and 4.17.1 Cross-Organization Account Takeover via Passkey Enrollment
    37Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2025-67717Dec 11, 2025 · Zitadel Discloses the Total Number of Instance Users
    21Monitor
  • ← EarlierCVE-2026-23511Jan 15, 2026 · ZITADEL has a user enumeration vulnerability in Login UIs
    21Monitor
  • Later →CVE-2026-27945Feb 25, 2026 · ZITADEL has potential SSRF via Actions
    8Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Go:github.com/zitadel/zitadel1.80.0-v2.20.0.20260216092519-feab8e1fa371Package registry (OSV)
Go:github.com/zitadel/zitadel3.4.7Package registry (OSV)
Go:github.com/zitadel/zitadel4.11.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

—

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-55671135 days apartZITADEL: Server-Side Request Forgery (SSRF) and Denylist Bypass in Outgoing HTTP Components
    9Monitor
  • CVE-2026-279450 days apartZITADEL has potential SSRF via Actions
    8Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-302 · Authentication Bypass by Assumed-Immutable Data

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records