# [CRIT] LiteLLM Flaw CVE-2026-42271 Exploited in the Wild, Chains to Unauthenticated RCE

**Source:** The Hacker News
**Published:** 2026-06-09
**Article:** https://thehackernews.com/2026/06/litellm-flaw-cve-2026-42271-exploited.html

## Threat Profile

LiteLLM Flaw CVE-2026-42271 Exploited in the Wild, Chains to Unauthenticated RCE 
 Ravie Lakshmanan  Jun 09, 2026 Vulnerability / Artificial Intelligence 
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Monday added a high-severity flaw impacting BerriAI LiteLLM to its Known Exploited Vulnerabilities ( KEV ) catalog, citing evidence of active exploitation.
The vulnerability, tracked as CVE-2026-42271 (CVSS score: 8.7), is a command injection vulnerability that could allow a…

## Indicators of Compromise (high-fidelity only)

- **CVE:** `CVE-2026-42271`
- **CVE:** `CVE-2026-48710`
- **CVE:** `CVE-2026-42208`

## MITRE ATT&CK Techniques

- **T1190** — Exploit Public-Facing Application
- **T1566.002** — Spearphishing Link
- **T1204.001** — User Execution: Malicious Link
- **T1059.001** — PowerShell
- **T1566.001** — Spearphishing Attachment
- **T1204.002** — User Execution: Malicious File
- **T1059.005** — Visual Basic
- **T1218** — System Binary Proxy Execution
- **T1528** — Steal Application Access Token
- **T1098.001** — Account Manipulation: Additional Cloud Credentials
- **T1219** — Remote Access Software
- **T1195.002** — Compromise Software Supply Chain
- **T1059** — Command and Scripting Interpreter
- **T1059.004** — Command and Scripting Interpreter: Unix Shell
- **T1078** — Valid Accounts

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### LiteLLM CVE-2026-42271 MCP test endpoint POST (preview command injection)

`UC_92_7` · phase: **exploit** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime values(Web.url) as url values(Web.src) as src values(Web.http_user_agent) as ua values(Web.status) as status from datamodel=Web.Web where Web.http_method=POST (Web.uri_path="/mcp-rest/test/connection" OR Web.uri_path="/mcp-rest/test/tools/list") by Web.dest Web.uri_path | `drop_dm_object_name(Web)` | where status<500 | sort - lastTime
```

### LiteLLM proxy (uvicorn/python) spawning shell or LOLBin — CVE-2026-42271 post-exploit

`UC_92_8` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime values(Processes.process) as cmd values(Processes.parent_process) as parent_cmd values(Processes.user) as user from datamodel=Endpoint.Processes where (Processes.parent_process_name IN ("python","python3","python.exe","python3.exe","uvicorn","uvicorn.exe","gunicorn")) (Processes.parent_process="*litellm*") (Processes.process_name IN ("sh","bash","dash","zsh","cmd.exe","powershell.exe","pwsh","curl","wget","nc","ncat","nslookup","dig","whoami","id","uname","chmod","base64")) by Processes.dest Processes.process_name Processes.parent_process_name Processes.user | `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName in~ ("python","python3","python.exe","python3.exe","uvicorn","uvicorn.exe","gunicorn")
| where InitiatingProcessCommandLine has_any ("litellm","litellm.proxy","litellm.main","--port 4000")
| where FileName in~ ("sh","bash","dash","zsh","cmd.exe","powershell.exe","pwsh.exe","curl","wget","nc","ncat","nslookup","dig","whoami","id","uname","chmod","base64")
| where AccountName !endswith "$"
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessId, FolderPath, SHA256
| order by Timestamp desc
```

### Anomalous Host header to LiteLLM (Starlette CVE-2026-48710 BadHost bypass)

`UC_92_9` · phase: **exploit** · confidence: **Medium** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count values(Web.uri_path) as paths values(Web.src) as src values(Web.http_user_agent) as ua from datamodel=Web.Web where (Web.uri_path="/mcp-rest/test/connection" OR Web.uri_path="/mcp-rest/test/tools/list" OR Web.uri_path="/chat/completions" OR Web.uri_path="/v1/chat/completions" OR Web.uri_path="/key/generate") by Web.dest Web.http_host _time | `drop_dm_object_name(Web)` | eventstats values(http_host) as known_hosts by dest | where NOT match(http_host, "<expected-host-regex>") | sort - _time
```

### Phishing-link click correlated to endpoint execution

`UC_PHISH_LINK` · phase: **delivery** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Phishing-link click that drives endpoint execution within 60s ```
| tstats `summariesonly` earliest(_time) AS click_time
    from datamodel=Web
    where Web.action="allowed"
    by Web.src, Web.user, Web.dest, Web.url
| `drop_dm_object_name(Web)`
| rename user AS recipient, dest AS clicked_domain, url AS clicked_url
| join type=inner recipient
    [| tstats `summariesonly` count
         from datamodel=Email.All_Email
         where All_Email.action="delivered" AND All_Email.url!="-"
         by All_Email.recipient, All_Email.src_user, All_Email.url, All_Email.subject
     | `drop_dm_object_name(All_Email)`
     | rex field=url "https?://(?<email_domain>[^/]+)"
     | rename recipient AS recipient]
| join type=inner src
    [| tstats `summariesonly` earliest(_time) AS exec_time
         values(Processes.process) AS exec_cmd, values(Processes.process_name) AS exec_proc
         from datamodel=Endpoint.Processes
         where Processes.parent_process_name IN ("chrome.exe","msedge.exe","firefox.exe",
                                                   "outlook.exe","brave.exe","arc.exe")
           AND Processes.process_name IN ("powershell.exe","pwsh.exe","cmd.exe","mshta.exe",
                                            "rundll32.exe","regsvr32.exe","wscript.exe",
                                            "cscript.exe","bitsadmin.exe","certutil.exe",
                                            "curl.exe","wget.exe")
         by Processes.dest, Processes.user
     | `drop_dm_object_name(Processes)`
     | rename dest AS src]
| eval delta_sec = exec_time - click_time
| where delta_sec >= 0 AND delta_sec <= 60
| table click_time, exec_time, delta_sec, recipient, src, src_user, subject,
        clicked_domain, clicked_url, exec_proc, exec_cmd
| sort - click_time
```

**Defender KQL:**
```kql
// Phishing-link click that drives endpoint execution within 60s.
// Far higher fidelity than "every clicked URL" — most legitimate clicks
// never spawn a non-browser child process, so the join eliminates the
// 99% of noise that makes a raw click query unactionable.
let LookbackDays = 7d;
let SuspectClicks = UrlClickEvents
    | where Timestamp > ago(LookbackDays)
    | where AccountName !endswith "$"
    | where ActionType in ("ClickAllowed","ClickedThrough")
    | join kind=inner (
        EmailEvents
        | where Timestamp > ago(LookbackDays)
        | where DeliveryAction == "Delivered"
        | where EmailDirection == "Inbound"
        | project NetworkMessageId, Subject, SenderFromAddress, SenderFromDomain,
                  RecipientEmailAddress, EmailTimestamp = Timestamp
      ) on NetworkMessageId
    | join kind=leftouter (
        EmailUrlInfo | project NetworkMessageId, Url, UrlDomain
      ) on NetworkMessageId, Url
    | project ClickTime = Timestamp, AccountUpn, IPAddress, Url, UrlDomain,
              Subject, SenderFromAddress, SenderFromDomain, RecipientEmailAddress,
              ActionType;
// Correlate to a non-browser child process spawned within 60 seconds on
// the recipient's device.
DeviceProcessEvents
| where Timestamp > ago(LookbackDays)
| where InitiatingProcessFileName in~ ("chrome.exe","msedge.exe","firefox.exe",
                                         "outlook.exe","brave.exe","arc.exe")
| where FileName in~ ("powershell.exe","pwsh.exe","cmd.exe","mshta.exe",
                        "rundll32.exe","regsvr32.exe","wscript.exe","cscript.exe",
                        "bitsadmin.exe","certutil.exe","curl.exe","wget.exe")
| join kind=inner SuspectClicks on $left.AccountName == $right.AccountUpn
| where Timestamp between (ClickTime .. ClickTime + 60s)
| project ClickTime, ProcessTime = Timestamp,
          DelaySec = datetime_diff('second', Timestamp, ClickTime),
          DeviceName, AccountName, RecipientEmailAddress, SenderFromAddress,
          Subject, Url, UrlDomain, ActionType,
          FileName, ProcessCommandLine, InitiatingProcessFileName
| order by ClickTime desc
```

### Email attachment opened from external sender

`UC_PHISH_ATTACH` · phase: **delivery** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count
    from datamodel=Email.All_Email
    where All_Email.file_name!="-"
    by All_Email.src_user, All_Email.recipient, All_Email.file_name, All_Email.subject
| rename All_Email.recipient as user
| join type=inner user
    [| tstats `summariesonly` count
        from datamodel=Endpoint.Processes
        where Processes.parent_process_name IN ("OUTLOOK.EXE","winword.exe","excel.exe","powerpnt.exe")
          AND Processes.process_name IN ("cmd.exe","powershell.exe","wscript.exe","cscript.exe","mshta.exe","rundll32.exe","regsvr32.exe")
        by Processes.dest, Processes.user, Processes.parent_process_name, Processes.process_name, Processes.process
     | rename Processes.user as user]
```

**Defender KQL:**
```kql
let LookbackDays = 7d;
let MalAttachments = EmailAttachmentInfo
    | where Timestamp > ago(LookbackDays)
    | where AccountName !endswith "$"
    | project NetworkMessageId, RecipientEmailAddress,
              AttachmentFileName = FileName, AttachmentSHA256 = SHA256;
DeviceProcessEvents
| where Timestamp > ago(LookbackDays)
| where InitiatingProcessFileName in~ ("OUTLOOK.EXE","winword.exe","excel.exe","powerpnt.exe")
| where FileName in~ ("cmd.exe","powershell.exe","wscript.exe","cscript.exe",
                      "mshta.exe","rundll32.exe","regsvr32.exe")
| join kind=inner MalAttachments on $left.AccountUpn == $right.RecipientEmailAddress
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine,
          InitiatingProcessFileName, AttachmentFileName, AttachmentSHA256
```

### Office app spawning script/LOLBin child process

`UC_OFFICE_CHILD` · phase: **exploit** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.parent_process_name IN ("winword.exe","excel.exe","powerpnt.exe","outlook.exe","onenote.exe","mspub.exe","visio.exe")
      AND Processes.process_name IN ("cmd.exe","powershell.exe","pwsh.exe","wscript.exe","cscript.exe","mshta.exe","rundll32.exe","regsvr32.exe","wmic.exe","bitsadmin.exe","certutil.exe")
    by Processes.dest, Processes.user, Processes.parent_process_name, Processes.process_name, Processes.process
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where InitiatingProcessFileName in~ ("winword.exe","excel.exe","powerpnt.exe","outlook.exe","onenote.exe","mspub.exe","visio.exe")
| where FileName in~ ("cmd.exe","powershell.exe","pwsh.exe","wscript.exe","cscript.exe","mshta.exe","rundll32.exe","regsvr32.exe","wmic.exe","bitsadmin.exe","certutil.exe")
| project Timestamp, DeviceName, AccountName, InitiatingProcessFileName, FileName, ProcessCommandLine
```

### OAuth consent / suspicious app grant

`UC_OAUTH_ABUSE` · phase: **actions** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Authentication.Authentication
    where Authentication.action="success"
      AND Authentication.signature IN (
        "Consent to application",
        "Add app role assignment grant to user",
        "Add OAuth2PermissionGrant",
        "Add delegated permission grant")
    by Authentication.user, Authentication.app, Authentication.src, Authentication.signature
| `drop_dm_object_name(Authentication)`
```

**Defender KQL:**
```kql
CloudAppEvents
| where Timestamp > ago(7d)
| where ActionType in ("Consent to application.","Add OAuth2PermissionGrant.","Add delegated permission grant.")
| project Timestamp, AccountObjectId, AccountDisplayName, ActivityType,
          ActivityObjects, IPAddress, UserAgent
```

### RMM tool installed by non-IT user — remote-access utility for hands-on-keyboard

`UC_RMM_TOOLS` · phase: **install** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.process_name IN ("AnyDesk.exe","TeamViewer.exe","TeamViewer_Service.exe",
        "ScreenConnect.ClientService.exe","ConnectWiseControl.ClientService.exe",
        "atera_agent.exe","SplashtopStreamer.exe","RustDesk.exe","NinjaOne.exe","kaseya*.exe")
    by Processes.dest, Processes.user, Processes.process_name, Processes.process, Processes.parent_process_name
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where FileName in~ ("AnyDesk.exe","TeamViewer.exe","TeamViewer_Service.exe",
        "ScreenConnect.ClientService.exe","ConnectWiseControl.ClientService.exe",
        "atera_agent.exe","SplashtopStreamer.exe","RustDesk.exe","NinjaOne.exe")
   or FileName matches regex @"(?i)kaseya.*\.exe"
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine
```

### Trusted vendor binary / installer launching unusual children

`UC_SUPPLY_CHAIN` · phase: **exploit** · confidence: **Medium**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.parent_process_name IN ("setup.exe","installer.exe","update.exe")
      AND Processes.process_name IN ("powershell.exe","cmd.exe","rundll32.exe","regsvr32.exe","mshta.exe","wscript.exe","cscript.exe","wmic.exe","bitsadmin.exe")
    by Processes.dest, Processes.user, Processes.parent_process_name, Processes.process_name, Processes.process
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where InitiatingProcessFileName in~ ("setup.exe","installer.exe","update.exe")
| where FileName in~ ("powershell.exe","cmd.exe","rundll32.exe","regsvr32.exe","mshta.exe","wscript.exe","cscript.exe","wmic.exe","bitsadmin.exe")
| project Timestamp, DeviceName, AccountName, InitiatingProcessFileName, FileName, ProcessCommandLine
```

### IOC-driven hunts (use shared templates)

These are standard IOC-substitution hunts — the canonical SPL and KQL live once in [`_TEMPLATES.md`](../_TEMPLATES.md), so we don't repeat the same boilerplate on every CVE / hash / network-IOC briefing.

- **Asset exposure — vulnerability matches article CVE(s)** ([template](../_TEMPLATES.md#asset-exposure)) — phase: **recon**, confidence: **High**
  - CVE(s): `CVE-2026-42271`, `CVE-2026-48710`, `CVE-2026-42208`


## Why this matters

Severity classified as **CRIT** based on: CVE present, 10 use case(s) fired, 15 technique(s) inferred. Read the full article for actor attribution, tooling details, and any defanged IOCs in the body that aren't visible in the RSS summary.