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CVE-2026-35030 — Vulnerability in litellm — CVE Details

CRITICAL

LiteLLM: Authentication bypass via OIDC userinfo cache key collision

Published April 3, 2026Updated September 10, 2026Source: osv

Summary

### Impact When JWT authentication is enabled (`enable_jwt_auth: true`), the OIDC userinfo cache uses `token[:20]` as the cache key. JWT headers produced by the same signing algorithm generate identical first 20 characters. This configuration option is not enabled by default. **Most instances are not affected.** An unauthenticated attacker can craft a token whose first 20 characters match a legitimate user's cached token. On cache hit, the attacker inherits the legitimate user's identity and permissions. This affects deployments with JWT/OIDC authentication enabled. ### Patches Fixed in v1.83.0. The cache key now uses the full hash of the JWT token. ### Workarounds Disable OIDC userinfo caching by setting the cache TTL to 0, or disable JWT authentication entirely.

Advisory Timeline

  • First published April 3, 2026 (192 days ago).
  • Last revised September 10, 2026 — 159 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

pip
Update litellm to 1.83.0 or later
pip install "litellm>=1.83.0"

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: pypi (1).

PackageEcosystemAffectedFixed In
litellm
pypi
0.1.0, 0.1.1, 0.1.2, 0.1.201 (+723 more)1.83.0

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-287
    Improper AuthenticationMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.9 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
—
Confidentiality
—
Integrity
—
Availability
—

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N

References

Frequently Asked Questions

What is CVE-2026-35030?
LiteLLM: Authentication bypass via OIDC userinfo cache key collision This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.9/10).
How do I check if my project is affected by CVE-2026-35030?
CVE-2026-35030 affects litellm. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-35030 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
9.9

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-jjhc-v7c2-5hh6
PYSEC-2026-390

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