CVE-2026-13466

Executive Summary

CVE-2026-13466 is an incorrect calculation of buffer size vulnerability (CWE-131) in Altera Trusted Firmware running on the Hard Processor System (HPS) of SoC FPGA platforms. The flaw allows buffer overflows, affecting Trusted Firmware through version socfpga_v2.14.0. With a CVSS score of 8.1, this local vulnerability requires high privileges to exploit but can lead to high integrity and availability impact on the System on Chip environment, potentially compromising secure boot and trusted execution components.

Technical Analysis

The vulnerability resides in Altera's Trusted Firmware implementation for the HPS within SoC FPGA devices. The NVD description explicitly identifies an "Incorrect calculation of buffer size" vulnerability (CWE-131) that allows "Overflow Buffers." This class of vulnerability occurs when software allocates a buffer using an incorrect size calculation—typically due to integer overflow, off-by-one errors, or mismatched type sizes—leading to insufficient memory allocation relative to the data subsequently written to it.

In the context of Trusted Firmware, which provides secure services, boot chain integrity, and privileged execution environments on the HPS, a buffer overflow can undermine the security boundaries between secure and non-secure worlds. The CVSS vector indicates a local attack vector (AV:L), low attack complexity (AC:L), high privileges required (PR:H), no user interaction (UI:N), and a scope change (S:C), meaning the exploit affects resources beyond the vulnerable component's original security authority.

The impact subvector (C:L/I:H/A:H) shows low confidentiality impact, but high integrity and availability impact, suggesting the overflow can corrupt critical firmware structures or execution flow, potentially leading to persistent compromise or denial of service of the trusted execution environment.

The affected range is defined as "through socfpga_v2.14.0," indicating that all versions up to and including this release are vulnerable. No patch information is available from any tracked source, and patch confidence is 0/4—UNPATCHED.

No specific function names, file paths, or API endpoints are provided in the NVD description, so the analysis remains at the vulnerability-class level. The attack surface is the Trusted Firmware on HPS, accessible to an attacker with high privileges (e.g., via a compromised OS, hypervisor, or physical access to debug interfaces).

Exploitation Scenarios

No public PoC or exploit code is available for CVE-2026-13466. The attack chain is inferred from the vulnerability class (CWE-131) and the context of Trusted Firmware on HPS.

1. Reconnaissance/target identification: An attacker identifies a target device (e.g., Intel/Altera SoC FPGA) running Trusted Firmware version socfpga_v2.14.0 or earlier. This could be achieved through device fingerprinting, firmware image analysis, or physical access to debug ports (JTAG).

2. Triggering the flaw class: The attacker, possessing high privileges (e.g., root or kernel-level access on the HPS), sends crafted input to an interface that invokes the vulnerable buffer size calculation in Trusted Firmware. The specific trigger depends on the incorrect size calculation—likely an integer overflow or off-by-one that passes a size check but under-allocates a buffer.

3. Payload/execution method: The crafted input causes a buffer overflow, overwriting adjacent memory. Given the trusted nature of the firmware, this could allow modification of control structures, function pointers, or return addresses. However, without public details, the exact payload format (e.g., specific SMC calls, mailbox messages, or image metadata fields) cannot be confirmed. The attacker would need to understand the Trusted Firmware's internal interfaces, which are not described in the NVD entry.

4. Post-exploitation impact: Successful exploitation could lead to code execution within the Trusted Firmware context (secure world), allowing the attacker to bypass secure boot, extract secrets, or maintain persistent control over the device. The scope change (S:C) indicates the attacker could affect resources beyond the firmware itself, such as the non-secure OS or other system components. High integrity and availability impacts suggest potential for firmware corruption, denial of service, or permanent bricking.

Impact Assessment

The CVSS score of 8.1 reflects a high severity vulnerability. The local attack vector (AV:L) limits exploitation to attackers with local access or high privileges on the target system. However, the scope change (S:C) and high integrity/availability impacts mean that a successful exploit can compromise the entire SoC security architecture, including the secure world, potentially leading to persistent firmware-level compromise.

Business impact: Affected systems include SoC FPGA platforms used in networking, industrial control, automotive, and defense applications. A compromised Trusted Firmware could undermine device attestation, secure key storage, and trusted execution, leading to data breaches, service outages, or physical damage in critical infrastructure. The unpatched status (0/4 patch confidence) means organizations must rely on mitigations until Altera releases a fix.

Blast radius: Because the vulnerability is in the HPS Trusted Firmware, it affects the root of trust for the device. An attacker with high privileges (e.g., via a compromised non-secure OS) can escalate to the secure world, bypassing isolation. This could enable lateral movement across devices if secure boot or attestation is subverted—though no evidence of active exploitation or threat actor campaigns is available.

Detection Guidance

Sigma Rule

title: Potential Altera Trusted Firmware Buffer Overflow Exploit (CVE-2026-13466)
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects attempts to exploit buffer size miscalculation in Altera Trusted Firmware on HPS through anomalous local privilege escalation or firmware access patterns.
author: valtersit.com
date: 2026-05-12
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    Image|endswith:
      - '/dev/mem'
      - '/dev/kmem'
    CommandLine|contains:
      - 'socfpga'
      - 'trusted-firmware'
      - 'hps'
  condition: selection
falsepositives:
  - Legitimate firmware update tools
  - Debugging sessions by authorized administrators
level: high
tags:
  - attack.privilege_escalation
  - attack.t1068
  - cve.2026.13466

YARA Rule

rule CVE_2026_13466_Altera_Trusted_Firmware_Buffer_Overflow
{
    meta:
        description = "Detects Altera Trusted Firmware versions vulnerable to CVE-2026-13466 (buffer size miscalculation)"
        author = "valtersit.com"
        date = "2026-05-12"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-13466"
        severity = "high"
    strings:
        $ver1 = "socfpga_v2.14.0"
        $ver2 = "socfpga_v2.13"
        $ver3 = "socfpga_v2.12"
        $tf = "Trusted Firmware"
        $hps = "HPS"
    condition:
        ($tf and $hps) or any of ($ver*)
}

Suricata IDS Rule

alert ip any any -> any any (msg:"CVE-2026-13466 - Altera Trusted Firmware Buffer Overflow Attempt"; flow:to_server; content:"|00 00 00 00|"; depth:4; content:"socfpga"; nocase; distance:0; within:100; classtype:attempted-admin; sid:100013466; rev:1;)

Elastic Detection

process where process.name == "devmem" or process.name == "mmap" and
  process.args contains "socfpga" and
  process.args contains "0x" and
  process.parent.name in ("sh", "bash", "python", "perl")

Splunk SPL Query

index=main (source="/var/log/syslog" OR source="/var/log/kern.log") 
| search "socfpga" OR "trusted-firmware" OR "HPS" 
| search ("buffer" OR "overflow" OR "segfault" OR "oops") 
| stats count by host, process, message 
| where count > 5

Wazuh OSSEC Rule

<group name="altera,cve-2026-13466,">
  <rule id="100466" level="12">
    <decoded_as>syslog</decoded_as>
    <match>socfpga|trusted-firmware|HPS</match>
    <match>buffer|overflow|segfault|oops</match>
    <description>CVE-2026-13466: Potential Altera Trusted Firmware buffer overflow exploitation attempt</description>
    <mitre>
      <id>T1068</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

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

1. Immediate mitigations:

   • Restrict local access to the HPS and Trusted Firmware interfaces to only essential, highly trusted administrators.
   • Disable or lock down debug interfaces (JTAG, UART) in production environments.
   • Monitor for anomalous local privilege escalation or firmware access attempts using the detection rules above.
   • Apply the principle of least privilege to reduce the attack surface for PR:H exploitation.

2. Patch/upgrade steps:

   • No patch is currently available. Monitor Altera's official security advisories and the NVD entry for updates.
   • When a patch is released, upgrade Trusted Firmware to a version beyond socfpga_v2.14.0 as directed by the vendor.
   • Verify firmware integrity after upgrade using cryptographic signatures.

3. Long-term hardening:

   • Implement secure boot with rollback protection to prevent exploitation of firmware-level vulnerabilities.
   • Conduct regular firmware audits and fuzz testing of Trusted Firmware interfaces.
   • Isolate the HPS from non-secure components using hardware isolation (e.g., ARM TrustZone).
   • Develop and enforce a vulnerability management program for embedded firmware, including periodic updates and threat modeling.

References

• NVD Entry for CVE-2026-13466
• MITRE CWE-131: Incorrect Calculation of Buffer Size
• [Altera Trusted Firmware Repository](https://github.com/altera-opensource/trusted-firmware-a (returned 404 — verify manually)) (monitor for patches)
• CISA Known Exploited Vulnerabilities Catalog (CVE not currently listed)
• No public proof-of-concept, exploit code, or threat actor campaign has been identified for this CVE at the time of reporting.