Critical Authentication exploit reference

CVE-2026-12773 — BerriAI LiteLLM MCP Proxy Improper Authentication (CVE-2026-12773)

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.

Published Jun 21, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulDB

Moderate

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 1% (30-day exploitation probability)+9
Technical severity (critical)+10
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

1.02%

ahead of 63% of scored CVEs · Oct 14, 2026

Affects

BerriAI

Litellm

CVSS base

9.8

Critical · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (BerriAI Litellm, Litellm Litellm).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
BerriAI	Litellm	version 1.59.0version 1.59.1version 1.59.2version 1.59.3version 1.59.4version 1.59.5version 1.59.6version 1.59.7 and 1 more version 1.59.8	Vulnerable	CVE Program (cve.org) e CISA ADP
Litellm	Litellm	< 1.59.9	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.9	CVSS 4.0	Medium	—	—	VulDB via CVE Program (cve.org) e CISA ADP
5.5	CVSS 4.0	Medium	—	—	cna@vuldb.com via NIST National Vulnerability Database
9.8	CVSS 3.1	Critical	3.9	5.9	nvd@nist.gov via NIST National Vulnerability Database
7.3	CVSS 3.1	High	3.9	3.4	cna@vuldb.com via NIST National Vulnerability Database
7.3	CVSS 3.1	High	3.9	3.4	0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database
7.3	CVSS 3.1	High	—	—	VulDB via CVE Program (cve.org) e CISA ADP
7.3	CVSS 3.0	High	—	—	VulDB via CVE Program (cve.org) e CISA ADP
7.5	CVSS 2.0	High	10.0	6.4	cna@vuldb.com via NIST National Vulnerability Database
7.5	CVSS 2.0	High	—	—	VulDB via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.8 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-287 · Improper Authentication

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.02%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.

web/proxy/WAF logsnetwork IDS/IPSauthentication logs

Analysis and videos

CVE-2026-12773: BerriAI LiteLLM MCP Proxy Improper Authentication
A weakness in the MCP Proxy component of BerriAI LiteLLM, classified as CWE-287 Improper Authentication, is described as affecting versions up to 1.59.8. NVD assigns a CVSS v3.1 base score of 9.8 (critical), and the record notes a publicly available exploit, while CISA KEV does not list this CVE. Defenders should prioritize upgrading to 1.59.9 or later and limiting network exposure of the proxy.

Timeline

What happened to this CVE, newest first.

2026
Affected products added · berriai/litellm
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 9.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Jun 21, 2026 · VulDB

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

8 on the record

vuldb.com/cve/CVE-2026-12773
Third Party Advisory, VDB Entry, third-party-advisory, NIST National Vulnerability Database
bugzilla.redhat.com/show_bug.cgi
NIST National Vulnerability Database
vuldb.com/vuln/372515/cti
Permissions Required, VDB Entry, signature, permissions-required, NIST National Vulnerability Database
vuldb.com/submit/811282
Exploit, Third Party Advisory, VDB Entry, third-party-advisory, NIST National Vulnerability Database
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12773.json
NIST National Vulnerability Database
vuldb.com/vuln/372515
Third Party Advisory, VDB Entry, vdb-entry, technical-description, NIST National Vulnerability Database
access.redhat.com/security/cve/CVE-2026-12773
NIST National Vulnerability Database
gist.github.com/YLChen-007/3cfaad10a69d7a15e4d4d458cb53309e
Exploit, Third Party Advisory, exploit, NIST National Vulnerability Database

Elsewhere on this site

BerriAI
every CVE for this vendor

Authentication
same class

CWE-287
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-108575 BerriAI LiteLLM Secret Resolution main.py get_secret improper authorization 4d
Medium CVE-2026-108574 BerriAI LiteLLM Spend Tracking spend_management_endpoints.py ui_view_session_spend_logs authorization 4d
High CVE-2026-59822 BerriAI LiteLLM Improper Authentication Vulnerability KEV Jul 8, 2026
Medium CVE-2026-59819 LiteLLM: Local file read via request-supplied OIDC file references Jul 8, 2026
Medium CVE-2026-59820 LiteLLM: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') Jul 8, 2026
High CVE-2026-59821 LiteLLM: Custom Code Guardrails production endpoints bypass code safety checks Jul 8, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-12773 is "BerriAI LiteLLM MCP Proxy Improper Authentication (CVE-2026-12773)", rated Critical. It affects Litellm (BerriAI); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 1.02% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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