What is CVE-2026-42271?

CVE-2026-42271 is LiteLLM: Authenticated command execution via MCP stdio test endpoints. The supplied enrichment data classifies it as Remote Code Exec mapped to CWE-77 Command Injection; CWE-78 OS Command Injection.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Is there a public exploit?

28 public PoC repositories reported; 0 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS, EDR process telemetry, host service logs where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-42271 using CVSS 8.8, EPSS 83%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

Workarounds are not confirmed from current sources. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVhighRemote Code Execpublic exploit

CVE-2026-42271

LiteLLM: Authenticated command execution via MCP stdio test endpoints

Q: Is it in CISA KEV?

Yes. The supplied enrichment data lists CVE-2026-42271 in CISA KEV with 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.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

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.

Published May 8, 2026Updated Jul 15, 2026Sources: NVD, BerriAI (CNA), CISA, FIRST EPSS, GitHub, GitHub Security Advisory, Red Hat (VEX)

Triage

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

Exploitation

Confirmed

CISA KEV, listed Jun 8, 2026

EPSS

83%

ahead of 99.6% of scored CVEs

Affects

BerriAI

2 products listed

CVSS base

8.8

high · 2 sources

CISA SSVC assessment

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

CISA

Exploitation

Active

none · proof-of-concept · active

Automatable

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

The vendor's own words where we have them.

Upgrade litellm to 1.83.7 or later (pip advisory GHSA-v4p8-mg3p-g94g).

CISA 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.

Federal deadline Jun 22, 2026 — passed 62 days ago

Red Hat VEX · CVE-2026-42271

fixed8affected0not affected19

vendor_fix: For Red Hat OpenShift AI 2.25.8 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and full…

vendor_fix: For Red Hat OpenShift AI 3.3.4 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully…

vendor_fix: For Red Hat OpenShift AI 3.4.1 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully…

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
BerriAI	litellm	>= 1.74.2, < 1.83.7	Vulnerable
pip	litellm	>= 1.74.2, < 1.83.7	Vulnerable

Attack characteristics

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

Availability

High

Confidentiality

High

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

Low

User Interaction

None

Every base score collected

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

Score	Version	Severity	Expl.	Impact	Source
8.8	CVSS 3.1	high	2.8	5.9	NVD, CNA, GHSA, Red Hat (VEX)
8.7	CVSS 4.0	high	—	—	BerriAI (CNA)

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness & attack patterns

CWE-77Command Injection
CWE-78OS Command Injection

Inferred from the weakness class — not observed against this CVE.

CAPEC-242 · Code InjectionCAPEC-35 · Leverage Executable Code in Non-Executable Files

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Jun 8, 2026

Federal deadline

Jun 22, 2026

passed 62 days ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

Detection

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

Search application, proxy, and WAF logs for requests touching /mcp-rest/test/connection, /mcp-rest/test/tools/list.
Prioritize edge telemetry for network-reachable litellm.
Monitor for scanner or exploit-pattern traffic after 28 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPSEDR process telemetryhost service logs

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 8.8 (AV:N)
Jul 15, 2026 · NVD
Added to CISA KEV catalog
Jun 8, 2026 · CISA
Initial · CVE published
May 8, 2026 · NVD
Added · GHSA-v4p8-mg3p-g94g published (high)
Apr 25, 2026 · GitHub Security Advisory

References

12 on the record

github.com/BerriAI/litellm/releases/tag/v1.83.7-stable
Product, Release Notes, Vendor Advisory
github.com/BerriAI/litellm/security/advisories/GHSA-v4p8-mg3p-g94g
Mitigation, Patch, Vendor Advisory
access.redhat.com/errata/RHSA-2026:27784
Third Party Advisory
access.redhat.com/errata/RHSA-2026:28960
Third Party Advisory
access.redhat.com/errata/RHSA-2026:30056
Third Party Advisory
access.redhat.com/security/cve/CVE-2026-42271
Third Party Advisory
bugzilla.redhat.com/show_bug.cgi?id=2467924
Third Party Advisory
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42271.json
Third Party Advisory

Elsewhere on this site

BerriAIevery CVE for this vendor
pipevery CVE for this vendor
June 2026what else CISA listed
Remote Code Execsame class
CWE-77other pages naming this weakness

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 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 record1

What should defenders know first?

CVE-2026-42271 is LiteLLM: Authenticated command execution via MCP stdio test endpoints, a high vulnerability affecting litellm from BerriAI, pip. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 28 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 8.8 describes technical severity, while EPSS 83% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.