From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72266][LOW] fbdev: vesafb: fix memory leak in vesafb_probe() Date: Sun, 16 Aug 2026 06:37:54 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72266 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 124df55c7201d011a3fead2205685b6c47eae093 List-Id: CVE: CVE-2026-72266 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: fbdev: vesafb: fix memory leak in vesafb_probe() Commit: 124df55c7201d011a3fead2205685b6c47eae093 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=124df55c7201d011a3fead2205685b6c47eae093 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72266 Analysis date: Sun, 16 Aug 2026 06:37:54 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate / Low-like Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72266 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72266 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: LOW Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-72266 LOW CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';*CWE-401;*CWE-772;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:N';BEST CVSS score: '2.3';DESCR 'vesafb_probe did not free the option string returned by fb_get_options after vesafb_setup consumed it. This is a small memory leak in the fbdev vesafb probe path and does not show a UAF, OOB access, arbitrary write, or other memory corruption primitive. For the CVSS the PR:H is used because triggering or influencing this path normally requires administrative control over kernel boot or device configuration. The issue is not network reachable and has no practical confidentiality or integrity impact. Availability impact is none in the base score and at most low in a conservative resource leak interpretation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) YES LEAK UAF LINUS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 1. ActionableScore * Conservative score: 0 * Paranoid score: 0 * Final recommended bucket: **Ordinary Moderate / Low-like**:: 2. Signal breakdown * No remote reachable signal: vesafb_probe is not network exposed. * No local unprivileged trigger: influencing this path normally requires boot parameter or device configuration control. * Requires admin/root/control of boot or platform configuration: -2. * Legacy / non-default execution path: vesafb is a legacy fbdev boot/display path: -1. * No memory corruption signal: the patch only adds kfree(option) after vesafb_setup(option). * No real lifetime corruption: this is a missing free, not UAF, double free, stale pointer, refcount misuse, or RCU lifetime bug. * Availability impact is not realistically actionable: the leak is small and tied to probe/setup, not an obvious repeatable unprivileged exhaustion path. * Call-site confidence: high, because the relevant call sequence fb_get_options -> vesafb_setup -> kfree is directly present in the patch. 3. Reachability analysis The bug is reachable during vesafb device probing, typically at boot or early platform device initialization. A practical attacker would need administrative control over kernel boot options or device configuration to influence the option string or cause the probe path to run. Namespaces and containers do not meaningfully lower the privilege requirement because this is not exposed through an ordinary per-container syscall, netlink, procfs, or device data-plane interface. The path is not network reachable and is not a common repeatedly triggerable user API. 4. Severity interpretation This behaves like a Low-like cleanup issue rather than an actionable Moderate or Important kernel vulnerability. The demonstrated issue is a small memory leak caused by ownership transfer after fb_get_options. There is no supported UAF, OOB access, arbitrary write, type confusion, page-cache corruption, sensitive data exposure, or privilege escalation path. Theoretical resource exhaustion is not convincing because the allocation appears small and the probe path is not repeatedly triggerable by an unprivileged user. 5. One-sentence report phrase vesafb_probe failed to free the option string returned by fb_get_options, causing a small probe-time memory leak that requires administrative or boot configuration control to influence and has no realistic confidentiality, integrity, or privilege escalation impact. 6. Manual review recommendation NO MANUAL CHECK NEEDED. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED. This is a constrained memory leak cleanup with very low reachability and no concrete security primitive beyond negligible resource leakage. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: fbdev: vesafb: fix memory leak in vesafb_probe() Commit: 124df55c7201d011a3fead2205685b6c47eae093 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=124df55c7201d011a3fead2205685b6c47eae093 Commit description: Since commit 73ce73c ("fbdev: Transfer video= option strings to caller; clarify ownership") the string returned from fb_get_options() is expected to be freed by the caller. But the string is not freed in vesafb_probe(). Fix that by freeing the option string after setup. Fixes: 73ce73c ("fbdev: Transfer video= option strings to caller; clarify ownership") Cc: stable@vger.kernel.org Signed-off-by: Abdun Nihaal Reviewed-by: Thomas Zimmermann Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman Changed files: drivers/video/fbdev/vesafb.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=124df55c7201d011a3fead2205685b6c47eae093 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72266 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72266 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS score: 2.3 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: unknown Paranoid ActionableScore: 0 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).