CVE-2023-36820Network attack vector

Cross-application token acceptance via skipped audience validation

Published Oct 9, 2023 · Updated Sep 19, 2024

Improper access control in Micronaut Security 3.1.0 through 3.11.0 allows remote attackers to accept an OIDC token issued for another application. IdTokenClaimsValidator skips validation of the token aud claim when the issuer matches, so tokens from one OIDC client can be accepted by another client sharing that issuer. Exploitation requires multiple OIDC applications using the same identity provider with tokens intended to remain separate, resulting in unauthorized data access or changes bounded by the receiving application’s privileges.

CVSS severity6.5
Medium
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Micronaut Security 3.1.0 through 3.11.0 allows remote attackers to accept an OIDC token issued for another application. IdTokenClaimsValidator skips validation of the token aud claim when the issuer matches, so tokens from one OIDC client can be accepted by another client sharing that issuer. Exploitation requires multiple OIDC applications using the same identity provider with tokens intended to remain separate, resulting in unauthorized data access or changes bounded by the receiving application’s privileges.

The record

CVE
CVE-2023-36820
Published
Oct 9, 2023
Updated
Sep 19, 2024
Vendor
Micronaut Foundation
Product
Micronaut Security
Classifications
CWE-284, T1550.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.10.0, < 3.10.2
  2. Affected versionversion=>= 3.1.0, < 3.1.2
  3. Affected versionversion=>= 3.11.0, < 3.11.1
  4. Affected versionversion=>= 3.2.0, < 3.2.4
  5. Affected versionversion=>= 3.3.0, < 3.3.2
  6. Affected versionversion=>= 3.4.0, < 3.4.3
  7. Affected versionversion=>= 3.5.0, < 3.5.3
  8. Affected versionversion=>= 3.6.0, < 3.6.6
  9. Affected versionversion=>= 3.7.0, < 3.7.4
  10. Affected versionversion=>= 3.8.0, < 3.8.4
  11. Affected versionversion=>= 3.9.0, < 3.9.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Micronaut Foundation · Micronaut Securityversion=>= 3.10.0, < 3.10.2; version=>= 3.1.0, < 3.1.2; version=>= 3.11.0, < 3.11.1; version=>= 3.2.0, < 3.2.4; version=>= 3.3.0, < 3.3.2; version=>= 3.4.0, < 3.4.3; version=>= 3.5.0, < 3.5.3; version=>= 3.6.0, < 3.6.6; version=>= 3.7.0, < 3.7.4; version=>= 3.8.0, < 3.8.4; version=>= 3.9.0, < 3.9.6

Published CVSS scores

6.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
4.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1550.001Use Alternate Authentication Material: Application Access Token

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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