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Vulnerability record · CVE-2026-35030 · published 6 April 2026

CVE-2026-35030: Litellm improper authentication vulnerability

Litellm · Litellm

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.83.0, 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. Fixed in v1.83.0.

9.4 CVSS 4.0 Critical EPSS 0.88% · top 42.5% CWE-287 · Improper authenticationCWE-222 · CWE-222
9.4CVSS 4.0 base score
0.88%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References
15 Jul 2026Last modified by NVD

Description

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.83.0, 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. Fixed in v1.83.0.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/BerriAI/litellm/security/advisories/GHSA-jjhc-v7c2-5hh6 MitigationVendor Advisory
https://access.redhat.com/errata/RHSA-2026:13545
https://access.redhat.com/errata/RHSA-2026:28960
https://access.redhat.com/errata/RHSA-2026:30056
https://access.redhat.com/security/cve/CVE-2026-35030
https://bugzilla.redhat.com/show_bug.cgi?id=2455509
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35030.json

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-35030), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.