CVE-2026-41425: Authlib Cross-site Request Forging When Using Vulnerability

MODERATE
Advisory Identifier: GHSA-jj8c-mmj3-mmgv
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CVSS 5.4
CWE-352
Published
Advisory Summary

CVE-2026-41425 is a MODERATE (CVSS 5.4) cross-site request forging when using vulnerability (CWE-352: Cross-Site Request Forgery (CSRF)) affecting Authlib libraries in the PyPI ecosystem. The issue involves cross-site request forging when using cache. Remediation is available by upgrading affected packages to version 1.6.11.

CVE-2026-41425 at a Glance

CVE Identifier CVE-2026-41425
GHSA Identifier GHSA-jj8c-mmj3-mmgv
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-352: Cross-Site Request Forgery (CSRF)
Affected Product Authlib
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-41425

To remediate this vulnerability, upgrade all affected Authlib dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

authlib fixed: 1.6.11 
pip install authlib>=1.6.11
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show authlib

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-41425, inspect your installed packages using pip:

pip show authlib

Analyze the terminal output to locate any version of Authlib in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.6.11), your application is affected.

Note: The pip show authlib command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-352: Cross-Site Request Forgery (CSRF), where the web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor. In Authlib, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary There is no CSRF protection on the cache feature on most integrations clients. ### Details In `authlib.integrations.starlette_client.OAuth`, no CSRF protection is set up when using the cache parameter. When _not_ using the cache parameter, the use of SessionMiddleware ties the client to the auth state, preventing CSRF attacks. With the cache, there is no such mechanism. Other integratons have the same issue, it's not just starlette. The state parameter is taken from the callback URL and the state is fetched from the cache without checking that it is the same client calling the redirect endpoint as was the one that initiated the auth flow. This issue is documented in RFC 6749 section 10.12: https://datatracker.ietf.org/doc/html/rfc6749#section-10.12 ### PoC - Set up a Starlette integration with a cache - The attacker starts the auth flow up until before the callback URL is followed. - The attacked sends the redirect URL to the victim - The victim now completes the authorisation ### Impact This impacts all users that use the cache to store auth state. All users will be vulnerable to CSRF attacks and may have an attacker's account tied to their own.

CVE-2026-41425 Affected Authlib Versions

1 component(s)
Fixed Versions:
1.6.11
Product / Package Ecosystem Affected Versions Fixed Version
authlib
pypi/authlib
PyPI
< 1.6.11
1.6.11

References

GitHub Advisory / Wiki ADVISORY
https://github.com/authlib/authlib/security/advisories/GHSA-jj8c-mmj3-mmgv
NVD — CVE-2026-41425 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-41425
Authlib Source Repository REPOSITORY
https://github.com/authlib/authlib
Authlib Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/authlib/PYSEC-2026-25.yaml

Frequently Asked Questions

What is CVE-2026-41425?
CVE-2026-41425 is a security vulnerability in Authlib involving Cross-site request forging when using cache under CWE-352: Cross-Site Request Forgery (CSRF).
Which Authlib versions are affected?
Affected versions include releases prior to 1.6.11 across affected packages: authlib.
What version fixes CVE-2026-41425?
Upgrading to 1.6.11 (or the latest patched release for your respective branch) resolves the vulnerability.
Is authlib affected?
Yes, authlib is affected in releases prior to 1.6.11. Upgrade your dependency to 1.6.11 or later.
What is the CVSS score of CVE-2026-41425?
CVE-2026-41425 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-41425?
CVE-2026-41425 is classified under CWE-352: Cross-Site Request Forgery (CSRF) (The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.).
How can I check PyPI dependencies for CVE-2026-41425?
Run the dependency tree command: 'pip show authlib'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jj8c-mmj3-mmgv",
  "modified" : "2026-06-05T14:29:21Z",
  "published" : "2026-04-16T22:38:03Z",
  "aliases" : [ "CVE-2026-41425" ],
  "summary" : "Authlib: Cross-site request forging when using cache",
  "details" : "### Summary\n\nThere is no CSRF protection on the cache feature on most integrations clients.\n\n### Details\nIn `authlib.integrations.starlette_client.OAuth`, no CSRF protection is set up when using the cache parameter. When _not_ using the cache parameter, the use of SessionMiddleware ties the client to the auth state, preventing CSRF attacks. With the cache, there is no such mechanism. Other integratons have the same issue, it's not just starlette.\n\nThe state parameter is taken from the callback URL and the state is fetched from the cache without checking that it is the same client calling the redirect endpoint as was the one that initiated the auth flow.\n\nThis issue is documented in RFC 6749 section 10.12:\nhttps://datatracker.ietf.org/doc/html/rfc6749#section-10.12\n\n### PoC\n- Set up a Starlette integration with a cache\n- The attacker starts the auth flow up until before the callback URL is followed.\n- The attacked sends the redirect URL to the victim\n- The victim now completes the authorisation\n\n### Impact\nThis impacts all users that use the cache to store auth state.\n\nAll users will be vulnerable to CSRF attacks and may have an attacker's account tied to their own.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "authlib"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.6.11"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/authlib/authlib/security/advisories/GHSA-jj8c-mmj3-mmgv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-41425"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/authlib/authlib"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/authlib/PYSEC-2026-25.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-352" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-16T22:38:03Z",
    "nvd_published_at" : "2026-04-24T20:16:27Z"
  }
}