CVE-2026-25302

Executive Summary

CVE-2026-25302 is a cryptographic verification weakness in Qualcomm Xrv9209 firmware that allows authentication and signature checks to be bypassed when processing non-ELF partitions. A local attacker with low privileges can mount and process unsigned or corrupted images, resulting in high confidentiality and availability impact (CVSS 7.1). The vulnerability remains unpatched with no public proof-of-concept or observed exploitation activity.

Technical Analysis

The vulnerability is classified under CWE-347 (Improper Verification of Cryptographic Signature). According to the NVD description, the firmware fails to properly validate cryptographic signatures and authentication data for non-ELF partition images. The integrity verification mechanism that should enforce signed firmware or partition images is either skipped, incorrectly applied, or trivially bypassable for non-ELF partition formats.

Non-ELF partitions are common in embedded and mobile firmware for storing configuration data, modem images, calibration tables, or vendor-specific blobs. Unlike ELF images, which may be validated by a stricter loader path, these partitions appear to be processed without equivalent signature enforcement. This creates an asymmetry in the chain of trust: an attacker able to supply or modify a non-ELF partition can bypass the cryptographic controls that protect ELF partitions.

The attack surface is local. The CVSS vector (AV:L) indicates the attacker requires local access or the ability to influence a local partition source. PR:L indicates low privileges are sufficient, and UI:N means no user interaction is required. The scope is unchanged (S:U), meaning the vulnerability impacts only the vulnerable component, but confidentiality and availability impacts are both High (C:H/I:N/A:H). Integrity impact is rated None at the CVSS level, likely because the bypass itself does not alter the integrity of protected data — it allows unauthorized images to be mounted, which then affect confidentiality and availability through processing of corrupted or malicious content.

Because no affected version list or patch details are provided, the exact firmware builds or device models impacted beyond Xrv9209 firmware cannot be enumerated. The description does not specify the cryptographic algorithm, signature scheme, partition parser, or the exact code path involved. Therefore, analysis is limited to the vulnerability class: improper signature verification of non-ELF partition images.

Exploitation Scenarios

No public PoC or exploit code is available. The attack chain below is inferred from the vulnerability class and the NVD description.

1. Reconnaissance/target identification: The attacker identifies a device running Qualcomm Xrv9209 firmware and determines that it processes non-ELF partitions. This may be done through device enumeration, firmware dump analysis, or knowledge of the device model. The attacker needs local access at low privilege (e.g., a shell, a compromised app, or physical access to a debug interface).

2. Triggering the flaw class: The attacker crafts or obtains an unsigned or corrupted non-ELF partition image. Because the firmware bypasses authentication and signature checks for non-ELF partitions, the image is accepted without cryptographic validation. The attacker then causes the device to mount or process this partition — for example, by placing it in a partition slot, triggering a firmware update path that handles non-ELF images, or rebooting the device to load the partition from storage.

3. Payload/execution method at the vulnerability-class level: The malicious or corrupted image is mounted and processed by the firmware. Depending on the partition's role, this could lead to execution of attacker-controlled data in the context of the partition processor, disclosure of sensitive information stored in or accessible to that partition, or a denial of service through corrupted data structures. The description does not specify a particular code execution primitive, so the exact post-mount behavior depends on the partition type and firmware implementation.

4. Post-exploitation impact: Successful exploitation yields high confidentiality impact (potential exposure of sensitive data processed by or stored in the partition) and high availability impact (device crash, hang, or loss of functionality due to corrupted images). Integrity impact is rated None at the CVSS level, but the practical effect is that the device operates on unverified data. The attacker may persist by repeatedly supplying malicious partitions or by leveraging the bypass to load modified configuration or modem data.

Impact Assessment

The CVSS score is 7.1 (High). The vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H indicates:

• Attack Vector (Local): The attacker must have local access or the ability to influence local partition sources. This limits remote exploitation but is achievable through physical access, debug interfaces, or a foothold on the device.
• Attack Complexity (Low): No special conditions are required beyond supplying a non-ELF partition image; the bypass is inherent to the firmware's handling of such partitions.
• Privileges Required (Low): The attacker does not need elevated privileges to trigger the flaw.
• User Interaction (None): No victim action is needed; the device processes the partition automatically.
• Scope (Unchanged): The impact is confined to the vulnerable component.
• Confidentiality (High): Sensitive data processed by or accessible to the partition may be exposed.
• Integrity (None): The bypass does not directly corrupt protected data, but it allows unverified data to be used.
• Availability (High): Corrupted or malicious images can cause device instability, crashes, or loss of service.

Affected systems are devices running Qualcomm Xrv9209 firmware. The blast radius depends on deployment: enterprise mobile devices, IoT endpoints, or embedded systems using this firmware. Because the flaw is local, mass exploitation would require a widespread local access vector. However, in environments where devices are physically accessible or where low-privilege code execution is common, the risk is significant.

Detection Guidance

Sigma Rule

title: Qualcomm Xrv9209 Non-ELF Partition Signature Bypass
id: 8f4a2c1e-9b3d-4e7a-8c2f-1a5b6d7e8f9a
status: experimental
description: Detects attempts to mount or process unsigned or corrupted non-ELF partition images on Qualcomm Xrv9209 firmware.
author: Threat Intelligence Team
date: 2026-01-15
logsource:
  product: linux
  service: kernel
detection:
  selection:
    EventType: 'partition_mount'
    PartitionType: 'non-elf'
    SignatureStatus: 'bypassed'
  condition: selection
falsepositives:
  - Legitimate firmware updates with properly signed non-ELF partitions
level: high
tags:
  - attack.t1553
  - cve.2026.25302

YARA Rule

rule CVE_2026_25302_Non_ELF_Partition_Bypass
{
    meta:
        description = "Detects non-ELF partition images that may exploit CVE-2026-25302 signature bypass"
        author = "Threat Intelligence Team"
        date = "2026-01-15"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-25302"
        severity = "high"

    strings:
        $magic_elf = { 7F 45 4C 46 }
        $part_header = "PARTITION" ascii wide nocase
        $sig_bypass = "signature" ascii wide nocase
        $non_elf = "NON_ELF" ascii wide nocase

    condition:
        not $magic_elf and ($part_header or $non_elf) and filesize < 10MB
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-25302 Qualcomm Xrv9209 Non-ELF Partition Signature Bypass Attempt"; flow:to_server,established; content:"|50 41 52 54 49 54 49 4F 4E|"; nocase; content:"|4E 4F 4E 5F 45 4C 46|"; nocase; distance:0; within:64; classtype:attempted-admin; sid:100025302; rev:1; reference:cve,2026-25302;)

Elastic Detection

process where process.name == "mount" and process.args : "*non-elf*" and process.args : "*partition*"

Splunk SPL Query

index=main (sourcetype=linux_secure OR sourcetype=syslog)
| search "non-ELF" OR "signature bypass" OR "partition mount" (CVE-2026-25302 OR Xrv9209)
| stats count min(_time) as firstTime max(_time) as lastTime by host, user, process, message
| where count > 0

Wazuh OSSEC Rule

<group name="qualcomm,xrv9209,">
  <rule id="100302" level="12">
    <decoded_as>json</decoded_as>
    <field name="event_type">partition_mount</field>
    <field name="partition_type">non-elf</field>
    <field name="signature_status">bypassed</field>
    <description>CVE-2026-25302: Non-ELF partition signature bypass detected on Qualcomm Xrv9209 firmware.</description>
    <mitre>
      <id>T1553</id>
    </mitre>
    <group>cve_2026_25302,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate mitigations:

   • Restrict local access to affected devices to trusted personnel only. Disable debug interfaces, ADB, or any local shell access where feasible.
   • Implement application allowlisting or integrity monitoring to detect unexpected partition mounts or firmware modifications.
   • If the device supports secure boot or verified boot with enforced signature checks, ensure it is enabled and configured to reject non-ELF partitions lacking valid signatures.
   • Monitor logs for partition mount events involving non-ELF images and investigate anomalies.

2. Patch/upgrade steps:

   • No vendor patch is currently available. Contact Qualcomm or the device OEM for status on a firmware update addressing CVE-2026-25302.
   • When a patch is released, apply it through the official firmware update channel and verify the update's signature.

3. Long-term hardening:

   • Enforce signature verification for all partition types, including non-ELF, in firmware design and procurement requirements.
   • Adopt hardware-backed secure boot and rollback protection to prevent loading of unauthorized images.
   • Conduct regular firmware integrity audits and penetration testing focused on partition handling.
   • Track Qualcomm security bulletins and CVE databases for patch availability.

References

• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25302
• CWE-347: Improper Verification of Cryptographic Signature — https://cwe.mitre.org/data/definitions/347.html
• MITRE ATT&CK T1553: Subvert Trust Controls — https://attack.mitre.org/techniques/T1553/
• Qualcomm Security Bulletins: https://www.qualcomm.com/company/product-security/bulletins
• CISA KEV Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CVE-2026-25302 not listed as of report date)

No public proof-of-concept, exploit code, or threat actor campaigns have been observed for CVE-2026-25302 at the time of writing.