CVE-2026-25262

Executive Summary

CVE-2026-25262 is a memory corruption vulnerability in the Qualcomm Mdm9207 firmware primary bootloader that can be triggered while the bootloader processes a crafted ELF (Executable and Linkable Format) file. Because the flaw resides in pre-operating-system boot code, successful triggering can undermine the hardware root of trust before any OS-level security controls are active. The CVSS v3.1 base score is 6.9 (Medium), with a physical attack vector, high attack complexity, and required user interaction, indicating the vulnerability is not remotely exploitable without adjacent access and a crafted input — but when exploited it yields high confidentiality, integrity, and availability impact under a changed scope. No public PoC, Nuclei template, or exploit code is currently available, and the vulnerability is listed as UNPATCHED across tracked sources.

The affected product is Qualcomm Mdm9207 firmware, a modem/platform chipset used in embedded and mobile deployments. The primary bootloader is the earliest-stage code that runs before the operating system and is responsible for initializing and authenticating subsequent boot stages. Corruption at this stage is significant because it can compromise the chain of trust, potentially allowing persistent, difficult-to-detect modification of a device's boot state. At the time of writing, no affected version ranges have been enumerated, no vendor advisory or patch reference has been published, and there is no evidence of exploitation in the wild (CISA KEV: NO; EPSS 0.00216, ~10.9th percentile).

Technical Analysis

The vulnerability is classified as CWE-123 (Write-what-where Condition), a memory corruption class in which attacker-influenced data is written to an attacker-influenced location within memory. The NVD description states the corruption occurs "while processing a crafted ELF file in the Primary Bootloader." The combination of CWE-123 with the ELF-parsing context suggests that the bootloader's ELF parsing routine fails to properly validate fields, sizes, or offsets within a malformed ELF, resulting in an out-of-bounds or uncontrolled write.

The attack surface is the bootloader's ELF loading/verification path. In embedded and mobile boot flows, a primary bootloader may consume an ELF — for example an early-stage or auxiliary image handed to it during the boot sequence. A crafted ELF provided through that path is processed before OS-level protections and runtime memory mitigations are established, meaning exploitation outcomes occur in the most privileged execution context on the device.

Several points must be stated explicitly to avoid overstatement:

• The NVD description does not name specific functions, fields, offsets, or memory regions. Accordingly, no specific ELF structure (program headers, section headers, entry point, symbol table, etc.) can be attributed as the trigger.
• The BSS/segment/heap/stack location of the corrupted memory is not stated and should not be assumed.
• The exact mechanism (integer overflow leading to undersized allocation, out-of-bounds write, or a write-what-where primitive from unvalidated addressing) is not disclosed. CWE-123 indicates the class of corruption, not the specific code path.

The CVSS vector (AV:P/AC:H/PR:L/UI:R/S:C) is consistent with a scenario requiring physical or tightly coupled access, substantial attacker knowledge of the target's image format and memory layout, low privilege to initiate the process, and interaction from a user or operator to supply or induce the crafted ELF. The Scope:Changed (S:C) subscore indicates the impact crosses an authorization boundary — consistent with bootloader corruption affecting security domains beyond the vulnerable component itself. High impacts across Confidentiality, Integrity, and Availability (C:H/I:H/A:H) reflect the potential to fully compromise device trust if the write primitive is reliably controlled.

Because this is primary bootloader code on a modem/platform chipset, boot firmware is typically signed and the boot chain uses authentication before executing later stages. That means the crafted ELF must generally be accepted by the boot flow (via an authorized update/flash channel or adjacent physical access) before the vulnerable parsing code is reached — which is consistent with AC:H and PR:L/UI:R. The absence of a disclosed vulnerable component version and the absence of any patch reference mean defenders cannot presently map a fixed build; the affected version field must remain "Not specified" until a vendor advisory enumerates it.

Exploitation Scenarios

No public PoC is available for CVE-2026-25262, and the vendor has published no advisory. The attack chain below is inferred at the vulnerability-class level from the NVD description and the reported CVSS vector; it does not assume undocumented function names, file paths, or API parameters.

1. Reconnaissance / target identification. The attacker identifies a device or platform running Qualcomm Mdm9207 firmware whose boot chain processes an ELF image, and determines the channel by which an ELF can be supplied to the primary bootloader (for example, a firmware update/flash mechanism, a service/repair interface, or an adjacent-access boot mode). The high attack complexity (AC:H) implies the attacker must build target-specific knowledge of the image format, boot sequence, and memory layout before attempting the attack.

2. Triggering the flaw class. The attacker constructs a malformed ELF — one whose structure violates the assumptions of the bootloader's ELF parser — and presents it to the vulnerable parsing path. Per CWE-123, the parser performs a write to a location influenced by the crafted file rather than to a validated, bounded destination. The specific malformed field(s) are not disclosed by the description and cannot be enumerated here.

3. Execution method. Because the corruption occurs pre-OS, there is no conventional "payload delivery" stage using OS processes or network protocols. Instead, the crafted ELF itself is the delivery vehicle, and the result of the uncontrolled write is the corruption of bootloader-controlled memory. Depending on how the write primitive is realized (not disclosed), outcomes could range from denial of boot to modification of bootloader control data. The published CVSS vector indicates the outcome is severe enough to cross a security scope boundary with high C/I/A impact, but the report does not claim a specific control-flow hijack, code-execution technique, or persistence mechanism, as none is described in the available data.

4. Post-exploitation impact. If the write primitive is reliably controlled, the primary bootloader — the foundation of the device's chain of trust — can be corrupted before OS-level defenses exist. That enables potential persistent alteration of the boot state, integrity compromise of the platform, and potential loss of confidentiality for data the boot stage is trusted to protect. Physical/adjacent access is a prerequisite under the published vector.

Caveat: the vendor has not confirmed exploitability, and no exploit code, Nuclei template, or in-the-wild activity has been observed. Treat the above as a threat-modeling scenario, not a validated exploit path.

Impact Assessment

Business impact centers on loss of boot-chain integrity. Because the affected component is a primary bootloader, exploitation can bypass the protections that ordinarily constrain an attacker post-boot, and remediation cannot rely on the operating system. The CVSS subscores translate as follows:

• Attack Vector: Physical (AV:P) — an attacker must have physical or tightly coupled access to the target device or boot interface.
• Attack Complexity: High (AC:H) — the attack depends on target-specific format knowledge and a favorable, non-trivial memory layout; success is not guaranteed and may require iteration.
• Privileges Required: Low (PR:L) — only low-level access to the boot/update mechanism is needed.
• User Interaction: Required (UI:R) — an operator action (for example, initiating a flash/update or placing the device in the relevant boot state) is necessary to supply the crafted ELF.
• Scope: Changed (S:C) — the exploit affects resources beyond the vulnerable component, meaning impact is expected to cross into the broader platform trust boundary.
• Confidentiality/Integrity/Availability: High (C:H/I:H/A:H) — potential full compromise of each property if the corruption is reliably controlled.

Affected systems are embedded/mobile devices built on Qualcomm Mdm9207 firmware whose boot path processes ELF images. Blast radius is device-level and, where fleet firmware is affected, potentially large across a deployed population. The high prerequisites (physical access plus user interaction) substantially limit mass exploitation, but the persistence potential and pre-OS nature of the flaw make individual-device compromise attractive for targeted attacks against high-value hardware.

Given CVSS 6.9 (Medium), an EPSS of 0.00216 (~10.9th percentile — indicating a low near-term exploitation probability), no CISA KEV listing, no PoC, and no patch, the strategic priority is (a) inventory of affected hardware, (b) hardening of boot/update channels, and (c) monitoring for publication of an authoritative vendor advisory. The absence of any patch source means there is currently no fixed build to correlate detections against.

Detection Guidance

Note: detection of a pre-OS bootloader flaw is necessarily constrained — there are no application logs inside the bootloader. The rules below target the observable proxies for this attack: shipment, transfer, or flashing of ELF images to Qualcomm-based devices, anomalous flashing activity, and malformed ELF characteristics on the associated host/tooling (which frequently runs Linux). Signatures should be tuned to environment-specific image tooling, paths, and network segments; the ELF field offsets referenced are generic format locations, not values disclosed by the CVE.

Sigma Rule

title: Suspicious ELF Image Flash to Qualcomm Bootloader
id: 7f3c2a10-9b44-4e21-b6d5-25262a000001
status: experimental
description: Detects staging or flashing of ELF images to Qualcomm (Mdm9207) boot interfaces, potential precursor to CVE-2026-25262 exploitation.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-25262
author: valtersit.com
date: 2026/02/01
logsource:
  product: linux
  category: process_creation
detection:
  selection_tools:
    Image|endswith:
      - '/fastboot'
      - '/edl'
      - '/qfiledl'
      - '/fh_loader'
      - '/qdl'
  selection_flash:
    CommandLine|contains:
      - 'flash'
      - 'download'
      - 'write'
      - 'elf'
  selection_img:
    CommandLine|contains: '.elf'
  condition: selection_tools and (selection_flash or selection_img)
falsepositives:
  - Authorized engineering, factory provisioning, and RMA flashing
  - Vendor firmware update tooling
level: medium
tags:
  - attack.t1542
  - cve.2026.25262

YARA Rule

rule CVE_2026_25262_Suspicious_ELF_Bootloader_Image
{
    meta:
        description = "Flags ELF images with malformed/oversized segment or section fields that may trigger CWE-123 memory corruption in a primary bootloader ELF parser (CVE-2026-25262). Generic format-level heuristic; not a CVE-specific byte signature."
        author = "valtersit.com"
        date = "2026-02-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-25262"
        cve = "CVE-2026-25262"
        severity = "medium"

    strings:
        $elf = { 7F 45 4C 46 }          // ELF magic
        $arm = { 28 00 }                // e_machine = EM_ARM (generic, endian-dependent)
        $aarch64 = { B7 00 }            // e_machine = EM_AARCH64 (generic, endian-dependent)

    condition:
        $elf at 0 and
        ($arm at 0x12 or $aarch64 at 0x12) and
        filesize < 64MB and
        // Example robustness gate: flag images that also carry an oversized embedded
        // segment descriptor (offset/count heuristic only; tune before production use).
        for any i in (0..1) : ( uint32(0x20 + (i * 0x20)) > filesize )
}

Suricata IDS Rule

alert tcp $HOME_NET any -> $HOME_NET any (msg:"CVE-2026-25262 Potential Crafted ELF Transfer to Qualcomm Bootloader Interface"; flow:established,to_server; content:"|7F 45 4C 46|"; depth:4; content:"|28 00|"; within:20; threshold: type both, track by_src, count 1, seconds 300; classtype:attempted-user; sid:202625262; rev:1; metadata:created_at 2026_02_01, cve CVE_2026_25262, affected_product Qualcomm_Mdm9207; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-25262;)

Elastic Detection

sequence by host.id with maxspan=5m
  [ process where process.name in ("fastboot", "edl", "qfiledl", "fh_loader", "qdl") and
      process.args : "*.elf" ]
  [ file where event.action in ("creation", "modification") and
      file.name : "*.elf" and file.size > 0 and
      process.name in ("fastboot", "edl", "qfiledl", "fh_loader", "qdl") ]

Splunk SPL Query

index=endpoint OR index=linux
| eval proc=lower(coalesce(process_name, Image, ""))
| eval cmd=coalesce(process_command_line, CommandLine, "")
| where match(proc, "(fastboot|edl|qfiledl|fh_loader|qdl)")
| where match(cmd, "(?i)\.elf") OR match(cmd, "(?i)(flash|download|write)")
| stats count min(_time) as first_seen max(_time) as last_seen
        values(cmd) as commands by host, user
| where count > 0
| convert ctime(first_seen) ctime(last_seen)
| table host, user, count, first_seen, last_seen, commands

Wazuh OSSEC Rule

<group name="qualcomm,bootloader,cve-2026-25262,">
  <rule id="202625262" level="9">
    <decoded_as>json</decoded_as>
    <field name="process.name">\.(fastboot|edl|qfiledl|fh_loader|qdl)$</field>
    <field name="process.command_line">\.elf</field>
    <description>CVE-2026-25262: Possible crafted ELF staged for Qualcomm bootloader flashing (fastboot/edl/qfiledl).</description>
    <mitre>
      <id>T1542</id>
    </mitre>
    <options>no_full_log</options>
  </rule>

  <rule id="202625263" level="10">
    <if_sid>202625262</if_sid>
    <field name="process.command_line">(flash|download|write)</field>
    <description>CVE-2026-25262: Bootloader flash/write command issued with ELF argument on Qualcomm target.</description>
    <mitre>
      <id>T1542</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No vendor fix, workaround, or fixed version is published in any tracked source (Affected Versions empty; Vendor Fix N/A). The recommendations below are compensating controls and general hardening measures, not vendor-confirmed fixes.

1. Immediate mitigations

• Restrict physical and adjacent access to devices and service/repair interfaces. Because the CVSS vector is AV:P with UI:R, physical access control and controlled flashing stations are the most effective near-term barriers.
• Enforce strict secure boot and boot-chain authentication policies, and disable or tightly gate any unauthenticated/development boot modes (for example, factory, download, or flashing modes) on production devices.
• Accept firmware and ELF images only from verified, cryptographically signed vendor sources; validate image signatures before they reach the boot flow wherever the boot ROM permits.
• Disable or remove any ELF flashing/transfer tooling from end-user and production devices where it is not operationally required, and require privileged, audited access for the tooling that remains.
• Log and monitor firmware update/download activity on host tooling, and monitor for anomalous flashing behavior (see Detection Guidance).

2. Patch/upgrade steps

• There is no patch to apply at this time. Continuously monitor the vendor (Qualcomm) security advisory channel and the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-25262) for an assigned fixed version or security bulletin.
• When a vendor fix becomes available, validate it against the affected Mdm9207 firmware, re-flash affected devices through an authenticated, audited maintenance window, and re-verify the boot-chain signature after update.
• Until a fix exists, keep the affected population on the latest known vendor-released firmware build and avoid unvetted third-party image sources.

3. Long-term hardening

• Adopt a hardware root-of-trust model that authenticates every boot stage, including the primary bootloader's parsing of any auxiliary images, and minimizes parsing of untrusted data at the earliest stages.
• Harden firmware supply chains: signed, reproducible firmware builds; image provenance tracking; and integrity verification at every flash and update step.
• Treat bootloader and pre-OS code as high-value attack surface in secure development lifecycle and penetration-testing programs, prioritizing memory-corruption classes (CWE-123 and related) in early-stage parsers.
• Add inventory and asset management for devices using Mdm9207 firmware so remediation can be scoped quickly once a patch is published.
• Maintain an EPSS- and KEV-driven watch process and reassess priority if this CVE appears in CISA KEV or if exploitation is reported (current status: not in KEV; EPSS 0.00216).

References

1. NVD — CVE-2026-25262: https://nvd.nist.gov/vuln/detail/CVE-2026-25262
2. CWE-123 — Write-what-where Condition: https://cwe.mitre.org/data/definitions/123.html
3. FIRST EPSS — Exploit Prediction Scoring System (score 0.00216, ~10.9th percentile): https://www.first.org/epss/
4. CISA Known Exploited Vulnerabilities Catalog (current status: CVE-2026-25262 NOT listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
5. Qualcomm Product Security / Security Bulletins (monitor for an advisory and fixed build for Mdm9207 firmware): https://www.qualcomm.com/company/product-security

No public PoC, Nuclei template, or exploit code is available for this CVE. There is no observed threat-actor campaign or exploit-in-the-wild evidence associated with CVE-2026-25262 at the time of writing.