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CVE-2026-59822 CISA KEV high CVSS 8.2

[KEV] Authentication Bypass in Berriai litellm (CVE-2026-59822)

Summary

Authentication bypass in Berriai litellm (CVE-2026-59822). Confidential information can be exposed externally. Exploitable via Authorization. Listed in CISA KEV — actively exploited. Mitigation: upgrade to 1.84.0 or later.

Original description

The description as published by the source.

Impact

LiteLLM's MCP Streamable HTTP endpoint could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token.

The MCP auth handler supported OAuth2 passthrough for upstream MCP servers, but the fallback path could replace failed LiteLLM key validation with an empty UserAPIKeyAuth() object. This allowed requests with a fabricated Authorization header to reach MCP tooling without a valid LiteLLM key.

An attacker could use this to list and call configured MCP tools and access connected services exposed through MCP.

Patches

The issue is fixed in 1.84.0.

We recommend upgrading to 1.84.0 or later.

Workarounds

If upgrading is not immediately possible, disable MCP routes or block access to /mcp/ and related MCP endpoints at your reverse proxy or API gateway.

References

Source: NIST National Vulnerability Database NVD GitHub Advisory CISA KEV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-59822 has been found in Berriai litellm.
Attackers can target a specific entry point like Authorization over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.2/10.
Note: CISA has officially confirmed this is actively exploited in the wild. Treat it with elevated urgency.
What to do: upgrade Berriai litellm to 1.84.0 or later.
If unsure, ask your IT team or search "Berriai litellm CVE-2026-59822" on the vendor's site.

CVE-2026-59822 (Berriai litellm) — CWE-287 / CVSS v3 8.2
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Authorization
Patched: 1.84.0 — apply immediately
Listed in CISA KEV — actively exploited, treat as top priority.
Workaround: If upgrading is not immediately possible, disable MCP routes or block access to /mcp/ and related MCP endpoints at your reverse proxy or API gateway.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Authentication bypass (CWE-287) exists in Berriai litellm. Attackers reach the vulnerable code path via Authorization without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Berriai litellm. Attack surface: Authorization.

🔥 Severity

Severity: High (CVSS 8.2/10). Confidential information can be exposed externally. Listed in CISA KEV — actively exploited in the wild, treat as top priority.

🔧 How to fix

Update to 1.84.0.

🛡️ Workaround

Workaround: If upgrading is not immediately possible, disable MCP routes or block access to /mcp/ and related MCP endpoints at your reverse proxy or API gateway.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'litellm' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'litellm' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で litellm を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Consider incident declaration escalate 
    Notify SOC / on-call

    CISA KEV登録済 = 実環境で悪用が観測されている。侵入の兆候があればインシデント対応宣言、無くてもパッチ適用までWAF強化を最優先で。

  3. 3
    Apply temporary workaround mitigate 
    If upgrading is not immediately possible, disable MCP routes or block access to `/mcp/` and related MCP endpoints at your reverse proxy or API gateway.

    パッチが適用されるまでの応急処置として、If upgrading is not immediately possible, disable MCP routes or block access to /mcp/ and related MCP endpoints at your reverse proxy or API gateway. を実施。回避策の副作用 (機能低下) を確認した上で。

  4. 4
    Apply patch patch 
    Upgrade Berriai litellm to 1.84.0

    ステージング環境で 1.84.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  5. 5
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

pip litellm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.84.0"}]}]
PyPI litellm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.84.0"}]}]

References

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