ExploitedIn CISA KEVFix available

CVE-2026-42271

Q: Is CVE-2026-42271 actively exploited?

Yes. CVE-2026-42271 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-06-22.

Q: What is the CVSS score for CVE-2026-42271?

CVE-2026-42271 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Exploitation confirmed. First attested on 2026-06-08 by CISA-ADP, CISA KEV, GCVE · kevintel, GCVE · shadowserver.

Published2026-05-08
Fixed in3.3.4 · 2.25.8
WeaknessCWE-77 · CWE-78

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.74.2 to before version 1.83.7, two endpoints used to preview an MCP server before saving it — POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list — accepted a full server configuration in the request body, including the command, args, and env fields used by the stdio transport. When called with a stdio configuration, the endpoints attempted to connect, which spawned the supplied command as a subprocess on the proxy host with the privileges of the proxy process. The endpoints were gated only by a valid proxy API key, with no role check. Any authenticated user — including holders of low-privilege internal-user keys — could therefore run arbitrary commands on the host. This issue has been patched in version 1.83.7.

Timeline

dates in UTC

2026-05-0804:16CVE publishedNVD
2026-06-08Listed as exploited by GCVEGCVE
2026-06-08Exploitation first reportedCISA KEV
2026-06-08Added to the CISA KEV catalogCISA KEV
2026-06-0817:47SSVC exploitation set to activeCISA-ADP
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-42271?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-42271?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Redhat openshift ai

Branch	Affected	Fixed in	Source
3.3	≥ 3.3, < 3.3.4	3.3.4	NVD
2.25	≥ 2.25, < 2.25.8	2.25.8	NVD
3.4	= 3.4	no fix published	NVD

Litellm

Branch	Affected	Fixed in	Source
1.x	≥ 1.74.2, < 1.83.7	1.83.7	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Redhat openshift ai to 3.3.4 · 2.25.8
CISA’s required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.due 2026-06-22

Advisories and patches

github.comRelease Notes
github.comMitigation · Patch · Vendor Advisory

Detection

read 2026-10-23 19:25 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 2 repositories, unverifiedlearner202649/CVE-2026-42271-PoCHORKimhab/CVE-2026-42271

CISA Known Exploited Vulnerability

Date Added: 2026-06-08
Patch Due Date: 2026-06-22
Ransomware Use: Unknown
Required Action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Sources

CISA KEVKEV entry2026-06-08
GCVEexploitation2026-06-08
CISA-ADPSSVC decisionactive2026-06-08
OpenCVESSVC decisionactive—
CNACVSS 4.08.7read 2026-10-23
CNACVSS 3.18.8read 2026-10-23
NVDCVSS 3.18.8read 2026-10-23
CNAweakness (CWE)CWE-77, CWE-78read 2026-10-23
FIRST EPSSEPSS score92.6 %read 2026-10-23
PoC-in-GitHubproof of concept2read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 4.0 vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/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:X/V:X/RE:X/U:X
Published: 2026-05-08
Last Modified: 2026-07-15
NVD status: Analyzed

Frequently asked questions

What is CVE-2026-42271?

Is CVE-2026-42271 actively exploited?

Yes. CVE-2026-42271 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-06-22.

What is the CVSS score for CVE-2026-42271?

CVE-2026-42271 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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