CVE-2026-12773: berriai litellm Improper Authentication
Vulnerability summary
CVE-2026-12773 is a critical (CVSS 9.8) Improper Authentication vulnerability in berriai litellm. EPSS estimates a 1.02% chance of exploitation in the next 30 days, higher than 62.7% of scored vulnerabilities. 2 public exploits are recorded.
Timeline
- 21-06-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
9 scores · 3 sources · 4 versions- OSV · PypiEcosystem advisory · calculated6.9MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- NVDNIST5.5MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/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:X/V:X/RE:X/U:XDiffers
- CVE.orgCNA7.3HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:RDiffers
- OSV · PypiEcosystem advisory · calculated7.3HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LDiffers
- NVDNIST7.5HighAV:N/AC:L/Au:N/C:P/I:P/A:P
EPSS trend
Probability
1.02%
Chance of exploitation in the next 30 days
Percentile
63%
Versus all other CVEs
30-day change
0.00 pp
From 1.02% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
2 found3Cfaad10A69D7A15E4D4D458Cb53309E
Maturity: poc
Exploit Reference (vuldb.com)
Maturity: unknown
Weaknesses
CWE · root cause- CWE-287Improper AuthenticationWhen an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
- CWE-303Incorrect Implementation of Authentication AlgorithmThe requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.
Affected systems
Berriai1 product
- litellm1.59.0 | 1.59.1 | 1.59.2 | 1.59.3 | 1.59.4 | 1.59.5 | 1.59.6 | 1.59.7 | 1.59.8
Litellm1 product
- litellm< 1.59.9
PyPI1 product
- litellm< 1.84.0
3 vendors · 3 products
References
13 links
Show all 13 references
- github.com/BerriAI/litellmPACKAGE
- pypi.org/project/litellmPACKAGE