CVE-2025-2486: 
NixOS vulnerability analysis and mitigation

CVE-2025-2486 is a Secure Boot bypass vulnerability in Ubuntu's edk2 UEFI firmware packages that accidentally allowed the UEFI Shell to be accessed in Secure Boot environments. The flaw is classified as an incomplete fix for CVE-2023-48733, where prior remediation efforts were insufficient to fully enforce Secure Boot restrictions. Affected versions include Ubuntu edk2 2024.05 (prior to 2024.05-2ubuntu0.3) and 2024.02 (prior to 2024.02-2ubuntu0.3). It carries a CVSS v3.1 base score of 8.8 (High) with a local attack vector (Feedly, Ubuntu Launchpad). The vulnerability was published on November 26, 2025, and assigned by Canonical.

The root cause is classified as CWE-489 (Active Debug Code), where the UEFI Shell — a powerful firmware-level interface — was inadvertently left accessible in Secure Boot environments due to an incomplete prior fix. Some earlier versions attempted to enforce Secure Boot by inserting a decision point within the Shell itself, but this approach was deemed insufficient. The attack vector is local with low attack complexity and requires only low privileges, meaning a local user with minimal access could invoke the UEFI Shell and interact with firmware outside the constraints of Secure Boot. This maps to CAPEC-121 (Exploit Non-Production Interfaces) and CAPEC-661 (Root/Jailbreak Detection Evasion via Debugging) (Feedly, Ubuntu Launchpad).

Successful exploitation allows an attacker to bypass Secure Boot restrictions and gain access to the UEFI Shell, enabling unauthorized modification of firmware settings and potentially executing unsigned or malicious code at the firmware level. This can compromise the fundamental integrity of the system's boot chain, undermining all higher-level security controls that depend on Secure Boot enforcement. The scope is marked as "Changed" in CVSS v3.1, reflecting that the impact extends beyond the vulnerable component to affect the broader system, with high confidentiality, integrity, and availability impacts (Feedly).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (Feedly). The EPSS score is extremely low at approximately 0.014%, indicating a very low probability of exploitation in the near term. The CVSSv4 exploit maturity is rated "UNREPORTED." The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Detection plugins are available via Nessus (plugin 260159) and Qualys (detection ID 6027809) (Feedly).

Ubuntu has released patched versions that fully disable the UEFI Shell in Secure Boot environments: edk2 2024.05-2ubuntu0.3 and edk2 2024.02-2ubuntu0.3. Users should update their Ubuntu edk2 packages immediately using the standard package manager (apt update && apt upgrade). Additionally, administrators should audit UEFI firmware configurations, enforce strict Secure Boot policies, and restrict physical and administrative access to affected systems. Monitoring for unauthorized firmware modifications is also recommended as a defense-in-depth measure (Feedly, Ubuntu Launchpad).

The vulnerability was noted by security community members on Mastodon (infosec.exchange) shortly after disclosure, and was tracked by multiple vulnerability aggregation platforms including VulnDB, CIRCL, and ENISA's EUVD. A blog post by Ubuntu developer Utkarsh Gupta (utkarsh2102.org) in December 2025 referenced the fix as part of FOSS work. Overall community reaction has been measured, given the lack of active exploitation and the availability of patches (Feedly).