medium CVSS 6.1

CVE-2026-44681·Python vulnerability

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.6.12 and 1.7.1, an unauthenticated open redirect in Authlib's OpenIDImplicitGrant and OpenIDHybridGrant authorization endpoint lets a remote attacker cause the authorization server to issue an HTTP 302 to an attacker-chosen URL by submitting an authorization request that omits the openid scope. This vulnerability is fixed in 1.6.12 and 1.7.1.

Severity
medium
Software
Python
Fixed in
1.6.12
Published
2026-05-27

Affected versions

Until: 1.6.12

Fixed in: 1.6.12

How to fix this CVE

Update Authlib to version 1.6.12 or later to patch the open redirect vulnerability in OpenID Connect authorization flows. The vulnerability allows attackers to manipulate redirect URIs when the openid scope is omitted from authorization requests. Ensure your OpenID Connect server implementation is running the patched version to prevent potential phishing attacks and unauthorized redirections.

sudo dnf update python3-authlib

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST /authorize HTTP/1.1.*redirect_uri=http[s]?://[attacker-domain].*(?!openid).*scope=

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement WAF rules to reject authorization requests with redirect_uri parameters pointing to external domains not in the allowlist, and enforce validation that the openid scope is present in all OpenID Connect authorization requests.

How to check if you are affected

  1. Check the installed Authlib version: python3 -c "import authlib; print(authlib.__version__)"
  2. Verify if your application uses OpenIDImplicitGrant or OpenIDHybridGrant: grep -r "OpenIDImplicitGrant\|OpenIDHybridGrant" /path/to/your/app --include="*.py"
  3. Review authorization endpoint logs for requests missing the openid scope parameter: grep -i "openid.*scope" /var/log/authlib*.log | grep -v "openid" | head -20
  4. Confirm the patch was applied by running: python3 -c "import authlib; assert authlib.__version__ >= '1.6.12'" && echo 'Patched' || echo 'Vulnerable'

FAQ

What is CVE-2026-44681?

CVE-2026-44681 is an open redirect vulnerability in Authlib's OpenID Connect authorization endpoints that allows unauthenticated attackers to redirect users to arbitrary URLs by crafting malicious authorization requests that omit the openid scope parameter.

Is CVE-2026-44681 being actively exploited?

No, CVE-2026-44681 is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available, but the vulnerability should still be patched promptly.

What versions of Authlib are affected by CVE-2026-44681?

All versions of Authlib prior to 1.6.12 and 1.7.1 are vulnerable. If you are running versions before these release dates, your installation is at risk.

How do I check if my server is vulnerable to CVE-2026-44681?

Run `python3 -c "import authlib; print(authlib.__version__)"` and compare the output to version 1.6.12 or 1.7.1. If your version is earlier, the server is vulnerable.

Does Defensia detect CVE-2026-44681?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Authlib is installed on a monitored server, CVE-2026-44681 will appear in your dashboard with remediation steps.

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References

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