From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72056][LOW] net: ena: clean up XDP TX queues when regular TX setup fails Date: Sat, 15 Aug 2026 22:06:25 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72056 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: 2 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: df65d9fea8437235e740552e542fb309765507db List-Id: CVE: CVE-2026-72056 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: net: ena: clean up XDP TX queues when regular TX setup fails Commit: df65d9fea8437235e740552e542fb309765507db Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=df65d9fea8437235e740552e542fb309765507db Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72056 Analysis date: Sat, 15 Aug 2026 22:06:25 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like. Auto-close candidate Manual review required: NO Summary: ENA queue setup may leak XDP TX queue resources when later regular TX setup fails, allowing a privileged or delegated local actor to cause resource exhaustion and local DoS under ENA and XDP TX specific conditions. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72056 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72056 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-72056 LOW CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-772;CWE-404;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'ENA queue setup can leak XDP TX queue resources when XDP TX queues are created successfully but the later regular TX resource setup or regular TX queue creation fails. Repeated failures during driver load, reset, or queue recreation can accumulate unreleased device queue resources and may eventually cause denial of service through resource exhaustion. For the CVSS the PR:L is used for the paranoid score because delegated network administration, driver management service accounts, or reduced capability root may be able to trigger queue recreation or reset paths in some deployments. The issue is not directly network reachable and requires the ENA driver and XDP TX related setup path to be present. Impact is denial of service only. No confidentiality or integrity impact is supported because the patch indicates a missing resource teardown, not UAF, OOB access, or an arbitrary write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Auto-close candidate (with actual score 1) YES REMOTE INIT LEAK ERRORPATH NETWORK HARDWARE LINUS TEST DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like. Auto-close candidate**:: ## 2. Signal breakdown Conservative signals: * Requires admin/root/CAP_NET_ADMIN in typical deployments: -2. Triggering queue recreation, driver reset, XDP setup, or ENA device management normally requires privileged network or device administration. * Rare AND difficult-to-reach subsystem/configuration: -1. Requires Amazon ENA, XDP TX queue setup, and a later failure in regular TX setup or queue creation. * Availability impact realistic: +1. Repeated failed setup/reset attempts could leak device queue resources and eventually cause local DoS or driver malfunction. Conservative raw score is below zero, normalized to 0. Paranoid additional signals: * Firmware-mediated external influence: +1. Regular TX queue creation may fail due to device or firmware behavior, though this is not the same as remote network reachability. * Reliable kernel crash / strong DoS: +1. Counted only in the paranoid interpretation, assuming repeated queue setup failures can realistically exhaust ENA resources or wedge the device. * Requires admin/root/CAP_NET_ADMIN in typical deployments: -1 instead of -2. In delegated cloud or containerized operations, a reduced-capability network management service account may be able to trigger reset or queue recreation paths. * Availability impact realistic: +1. Sustained abuse can plausibly cause resource exhaustion. * Rare AND difficult-to-reach subsystem/configuration: -1. No memory corruption signal is awarded. The patch fixes missing teardown of XDP TX queues and resources. It does not show UAF, OOB access, double free, arbitrary write, attacker-controlled reclaim, or type confusion. ## 3. Reachability analysis The bug is local and device/configuration dependent. A typical attacker would need administrative control over the ENA interface, driver reset, XDP setup, or queue recreation path. It is not directly network-triggerable by packets. Namespaces or containers may matter only if the environment delegates meaningful network administration or device reset control to a less privileged actor. In normal host deployments, this remains PR:H-like. In a paranoid cloud/container setting, PR:L-like handling is defensible for triage, but still only as DoS. The path is not universally default-exposed. It requires an ENA device and XDP TX related queue setup, plus failure of later regular TX setup. Call-site confidence: high. The affected setup and error paths are visible in the supplied patch. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource leak, not an Important-class kernel vulnerability. The realistic impact is local denial of service through resource exhaustion or device malfunction after repeated failed setup/reset cycles. Theoretical escalation beyond DoS is not supported. There is no evidence of memory corruption, stale pointer use, attacker-controlled overwrite, privileged data exposure, or cross-boundary security bypass. ## 5. One-sentence report phrase ENA queue setup may leak XDP TX queue resources when later regular TX setup fails, allowing a privileged or delegated local actor to cause resource exhaustion and local DoS under ENA and XDP TX specific conditions. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for urgent security triage because it is a resource leak in an error path, requires privileged or delegated device management conditions, is not network reachable, and has no supported memory corruption or privilege escalation primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net: ena: clean up XDP TX queues when regular TX setup fails Commit: df65d9fea8437235e740552e542fb309765507db Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=df65d9fea8437235e740552e542fb309765507db Commit description: create_queues_with_size_backoff() creates XDP TX queues before setting up the regular TX path. If the subsequent allocation or creation of regular TX queues fails, the error handling paths omit the teardown of the XDP TX queues, leading to a resource leak. Fix this by explicitly destroying the XDP TX queue subset at the two missing failure points. The bug was first flagged by an experimental analysis tool we are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under development and is not yet publicly available. Manual inspection confirms that the bug is still present in v7.1-rc7. An x86_64 allyesconfig build showed no new warnings. As we do not have an ENA device to test with, no runtime testing was able to be performed. Fixes: 548c494 ("net: ena: Implement XDP_TX action") Cc: stable@vger.kernel.org Signed-off-by: Dawei Feng Reviewed-by: Arthur Kiyanovski Tested-by: Arthur Kiyanovski Link: https://patch.msgid.link/20260616142424.4005130-1-dawei.feng@seu.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Changed files: drivers/net/ethernet/amazon/ena/ena_netdev.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=df65d9fea8437235e740552e542fb309765507db ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72056 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72056 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:H/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 0 Paranoid ActionableScore: 2 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).