CVE-2026-24239

Executive Summary

CVE-2026-24239 is a deserialization-of-untrusted-data vulnerability (CWE-502) in NVIDIA NeMo Speech that allows an attacker to achieve remote code execution by supplying malicious data to the affected component. The flaw carries a CVSS v3.1 base score of 7.8 (High), with the Local attack vector and User Interaction requirement reflecting that the victim must load or process attacker-controlled data for exploitation to succeed. Successful exploitation could result in code execution, information disclosure, and data tampering within the context of the NeMo Speech process, and no patch or public proof-of-concept is currently available.

Technical Analysis

NVIDIA NeMo Speech is a toolkit for automatic speech recognition, text-to-speech, and related speech-AI pipelines. The NVD description states that the product "contains a vulnerability where malicious data created by an attacker could cause remote code execution" and maps the issue to the unsafe-deserialization class, CWE-502. In this class of flaw, the application deserializes data from a source it should not trust — for example a model file, checkpoint, serialized object graph, audio-adjacent metadata artifact, or other structured input — and the deserialization logic reconstructs objects in a way that executes attacker-influenced code.

Because CWE-502 is language-agnostic and the NVD text does not name a specific function, class, module, file path, or API endpoint, the precise deserialization sink inside NeMo Speech cannot be identified from available data. What can be stated confidently is the vulnerability class and its consequence: when a user or service loads attacker-supplied data with NeMo Speech, object reconstruction can trigger code execution rather than merely parsing content. The CVSS vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) further implies the attack does not require network position or privileges, but does require the victim to interact with (load/process) the crafted data, and that a successful attack is contained to the NeMo Speech security scope while compromising confidentiality, integrity, and availability at High impact.

No technical details beyond the CWE classification, CVSS vector, and the CNA's impact statement are available. Function names, serialization formats, and affected artifact types should not be assumed.

Exploitation Scenarios

Exploitation is inferred from the CWE-502 vulnerability class; no public proof-of-concept exists.

1. Reconnaissance / target identification. An attacker identifies a host or pipeline that uses NVIDIA NeMo Speech, for example a workstation, inference server, or CI job that loads speech models, checkpoints, or data artifacts supplied by others. Because the NVD description references malicious data rather than a network service, the realistic delivery channel is a shared or externally sourced dataset/artifact rather than a remotely reachable port.

2. Triggering the flaw. The attacker crafts a malicious data artifact containing a serialized object payload that, when deserialized by the vulnerable NeMo Speech component, executes attacker-controlled code. The specific format is not disclosed; the mechanism is unsafe deserialization of untrusted input.

3. Payload / execution. On load, the deserialization routine reconstructs the attacker's object, resulting in code execution in the NeMo Speech process context. No specific gadget chains, function names, or file paths can be cited because none are disclosed.

4. Post-exploitation. Per the CNA, a successful exploit can lead to code execution, information disclosure, and data tampering — meaning the attacker may run code, exfiltrate data processed or accessible to NeMo Speech, and alter model/data artifacts.

This is a supply-chain-adjacent risk: malicious data typically propagates through shared model repositories, dataset exchange, or teammate/collaborator handoffs, and the UI:R vector means a user must load the tainted artifact.

Impact Assessment

CVSS v3.1 base 7.8 (High), vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H:

• AV:L (Local) — attack requires local access to the data path, not remote network reach.
• AC:L (Low) — no unusual conditions beyond loading the data.
• PR:N (None) — no privileges required by the attacker.
• UI:R (Required) — a user must load/process the malicious data.
• S:U (Unchanged) — impact stays within the NeMo Speech security scope.
• C/I/A:H — High impact to confidentiality, integrity, and availability.

Business impact centers on AI/ML pipelines: code execution on systems handling proprietary speech data or models, potential exfiltration of sensitive audio/transcripts or model IP, tampering with models or outputs (integrity risk to downstream decisions), and disruption of training/inference. Blast radius is limited to hosts that load untrusted NeMo Speech artifacts, but such hosts are often high-value (GPU nodes, data-science workstations, model-build servers).

Detection Guidance

Detection focuses on the observable indicators of loading untrusted serialized data: process activity, file writes, and anomalous outbound connections from NeMo Speech workloads. Rules below are class-level and should be tuned to the environment.

Sigma Rule

title: Suspicious Deserialization / Child Process by NVIDIA NeMo Speech
id: 8f5c2b1a-2423-9c1e-9a01-7d3e0f2b4c11
status: experimental
description: Detects abnormal child-process or network activity from NeMo Speech processes consistent with unsafe deserialization exploitation (CVE-2026-24239, CWE-502)
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-24239
author: valtersit.com
date: 2026/01/01
logsource:
  category: process_creation
  product: linux
detection:
  selection_parent:
    ParentImage|endswith:
      - '/python'
      - '/python3'
    CommandLine|contains:
      - 'nemo'
      - 'NeMo'
  selection_child:
    Image|endswith:
      - '/sh'
      - '/bash'
      - '/curl'
      - '/wget'
      - '/nc'
      - '/ncat'
      - '/powershell.exe'
      - '/cmd.exe'
  condition: selection_parent and selection_child
falsepositives:
  - Legitimate NeMo pipeline scripts invoking shell helpers
level: high

YARA Rule

rule CVE_2026_24239_NeMo_Serialized_Payload
{
    meta:
        description = "Detects serialized Python object markers often abused in CWE-502 deserialization attacks against NVIDIA NeMo Speech (CVE-2026-24239)"
        author = "valtersit.com"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-24239"
        cwe = "CWE-502"
    strings:
        $py_pickle  = { 80 04 95 }            // pickle protocol 4 opcode
        $py_global  = "c__builtin__" nocase
        $py_global2 = "cbuiltins" nocase
        $py_reduce  = "Rbuild" nocase
        $py_eval    = "eval(" nocase
        $py_exec    = "__reduce__" nocase
        $nemo       = "nemo" nocase
    condition:
        (uint16(0) == 0x8b3c or uint16(0) == 0x0880 or true) and
        ($py_pickle or ($py_global and $py_global2)) and
        ($py_reduce or $py_eval or $py_exec)
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-24239 Possible NVIDIA NeMo Speech Deserialization Exfil/Stager"; flow:established,to_server; content:"nemo"; http_client_body; nocase; content:"__reduce__"; http_client_body; nocase; content:"cbuiltins"; http_client_body; nocase; classtype:attempted-admin; sid:202624239; rev:1; metadata:created_at 2026_01_01, cve CVE-2026-24239, cwe CWE-502; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-24239;)

Note: This rule watches network egress of serialized-object markers from a host running NeMo Speech. If the malicious data is delivered via file share rather than HTTP, network telemetry may not observe it — rely on host-based detection in that case.

Elastic Detection

process where event.type == "start" and
  process.parent.name : ("python", "python3") and
  process.parent.command_line : "*nemo*" and
  process.name : ("sh", "bash", "curl", "wget", "nc", "ncat", "powershell.exe", "cmd.exe")

Splunk SPL Query

index=endpoint OR index=sysmon (EventCode=1)
| eval cmd=lower(CommandLine)
| where (like(lower(ParentCommandLine), "%nemo%") AND (like(cmd,"%curl %") OR like(cmd,"%wget %") OR like(cmd,"%bash %") OR like(cmd,"%/sh %") OR like(cmd,"%powershell%")))
| stats count min(_time) as first_seen by host, User, ParentCommandLine, CommandLine
| sort - count

Wazuh OSSEC Rule

<group name="nvidia_nemo,cve-2026-24239,">
  <rule id="202624" level="12">
    <if_sid>5920</if_sid>
    <field name="win.eventdata.parentImage">python|python3</field>
    <field name="win.eventdata.parentCommandLine">nemo</field>
    <field name="win.eventdata.image">powershell.exe|cmd.exe|curl.exe|wget.exe</field>
    <description>CVE-2026-24239: Possible deserialization code execution via NVIDIA NeMo Speech (CWE-502)</description>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>
  <rule id="202625" level="12">
    <if_sid>550</if_sid>
    <match>nemo</match>
    <regex>__reduce__|cbuiltins|c__builtin__</regex>
    <description>CVE-2026-24239: Suspicious serialized-object markers written by NeMo Speech process</description>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor advisory, workaround, or fixed version has been published as of this report.

1. Immediate mitigations

   • Treat all externally sourced NeMo Speech data, checkpoints, and serialized artifacts as untrusted; do not load them from shared drives, public repositories, or untrusted collaborators without validation.
   • Restrict loading of serialized artifacts to trusted sources, and require integrity verification (hash/signature) before use.
   • Run NeMo Speech workloads under least-privilege service accounts with egress filtering to limit post-exploitation code execution, data exfiltration, and tampering.
   • Isolate GPU/data-science hosts processing untrusted artifacts and monitor for unexpected child processes spawning from Python/NeMo processes.

2. Patch/upgrade steps

   • Monitor NVIDIA's security bulletin channel and the NVD entry for CVE-2026-24239 for an official fix or updated NeMo Speech release.
   • Once a fixed version is published, upgrade to that release and re-validate any artifacts that were previously loaded.

3. Long-term hardening

   • Adopt safe deserialization practices (avoid untrusted pickle/deserialization of third-party data; use safe formats such as JSON where practical).
   • Enforce a model/artifact supply-chain policy: signed artifacts, provenance tracking, and scanning of incoming data before pipeline ingestion.
   • Continuously monitor EPSS and CISA KEV for changes; re-prioritize if exploit activity emerges.

References

• NVD — CVE-2026-24239: https://nvd.nist.gov/vuln/detail/CVE-2026-24239
• CWE-502: Deserialization of Untrusted Data — https://cwe.mitre.org/data/definitions/502.html
• MITRE ATT&CK T1203 — Exploitation for Client Execution: https://attack.mitre.org/techniques/T1203/
• NVIDIA Product Security / security bulletins portal: https://www.nvidia.com/en-us/security/
• CISA Known Exploited Vulnerabilities catalog (check for inclusion): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No exploit-in-the-wild evidence, public PoC, Nuclei template, or threat-actor campaign has been observed for CVE-2026-24239 as of this report. CISA KEV status: not listed. EPSS: not yet scored by FIRST.org.