From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80898][LOW] netfs: clear PG_private_2 on copy-to-cache append failure [ Upstream Date: Fri, 04 Sep 2026 15:55:34 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80898 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: unknown X-AL-KERNEL-Commit: 627826ef4208042b0470d1a3fdb729ce35471a0d List-Id: CVE: CVE-2026-80898 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: netfs: clear PG_private_2 on copy-to-cache append failure [ Upstream Commit: 627826ef4208042b0470d1a3fdb729ce35471a0d Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=627826ef4208042b0470d1a3fdb729ce35471a0d Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80898 Analysis date: Fri, 04 Sep 2026 15:55:34 -0400 ActionableScore: 2 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80898 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80898 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-2026-80898 LOW https://www.kernelcve.org/list/?q=CVE-2026-80898 CHECK WITH IMPACT FROM ORIG NN MODERATE 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-401;CWE-404;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A netfs copy-to-cache failure can leave a folio marked with PG_private_2 and keep its extra reference after rolling_buffer_append fails. The folio is then not queued for cache writeback, but the private_2 state remains active, which can cause a reference leak and gradual resource exhaustion. For the CVSS the PR:L is used because a local user or process that can access a mounted netfs backed filesystem may trigger reads that enter this path, although reliable triggering also depends on cache configuration and append failure conditions. The issue is not directly network reachable as an attack against the kernel, even though netfs is commonly used with network filesystems. Impact is denial of service through resource leakage and memory pressure. No confidentiality or integrity impact is assigned because the patch indicates a missing release of a folio state and reference rather than UAF, OOB access, or an arbitrary write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) SKIP CVE-2026-80898 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE REMOTE DISK SIMPLEFIX LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2 * Raw paranoid score: 2 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap changed the score. 2. Signal breakdown Positive signals: * +1 Concrete persistent kernel resource/reference leak: the patch directly shows that PG_private_2 state and its associated folio reference were not released when rolling_buffer_append() failed. * +1 Local below-host-admin trigger: after a suitable netfs-backed cached filesystem is mounted, a local user or process with filesystem access can plausibly drive reads into this copy-to-cache path. Negative signals or non-awarded signals: * +0 Real UAF not awarded: the patch shows a missing folio_end_private_2() release, not stale post-free dereference. * +0 Concrete repeated release/refcount not awarded: there is no first release followed by a second lifetime mutation through the same dangling reference. * +0 Reliable kernel crash not awarded: the supplied evidence indicates a reference/resource leak, not an immediate panic or Oops. * +0 Extra availability not awarded: sustained exhaustion is possible in theory, but host-wide exhaustion is not demonstrated by the one-line fix. * +0 Confidentiality and integrity not awarded: no disclosure, arbitrary write, ownership bypass, or corruption primitive is established. * +0 Remote reachability not awarded: netfs may use network filesystems, but the vulnerable operation is not directly reachable by attacker network packets. * +0 Strong or weak LPE not awarded: no controlled reclaim, object replacement, arbitrary R/W, or privilege-boundary bypass is shown. 3. Reachability analysis The likely trigger is a local process reading from a mounted netfs-backed filesystem with copy-to-cache behavior active, where rolling_buffer_append() fails. The attacker does not need host administrator privilege merely to perform reads on an already mounted filesystem, so HostAdminRequired=NO for the runtime trigger. However, the mount and caching configuration are normally prior privileged setup, and reliable triggering depends on cache state, memory pressure, or rolling-buffer failure conditions. No namespace-scoped privilege is involved or needed in the supplied evidence, so NamespaceScopedPrivilege=NO. There is no direct network attack path against the kernel even though netfs is used by network filesystems. No special hardware is required. This is not a race; it is an error-path cleanup omission. 4. Primitive and severity interpretation The exact primitive is a missing release of PG_private_2 state and its folio reference after a failed append to the copy-to-cache rolling buffer. This is a concrete resource/reference leak, not a UAF, not a double release, not an OOB access, and not an ownership/COW violation. The affected folio is not queued for cache writeback after append failure, but the private_2 state remains set and the reference remains held. The demonstrated consequence is gradual resource leakage and possible memory pressure if the path is hit repeatedly. The speculative consequence is denial of service through accumulation, but the patch does not establish immediate host-wide failure or a stronger exploitation primitive. PrimitiveClass=NONE because no meaningful corruption, stale-object use, authorization bypass, or security-boundary primitive is established. ImportantCandidate=NO because the issue is a constrained resource leak without evidence of memory corruption or privilege escalation. AutoDowngradeAllowed=YES because automatic downgrade would not discard an unresolved corruption or boundary-bypass primitive. Likely operational severity is Low to ordinary Moderate. 5. One-sentence report phrase A netfs copy-to-cache append failure can leave a folio marked with PG_private_2 and keep its extra reference, causing a resource leak that may lead to denial of service only under repeated failure conditions. 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: this is a concrete resource/reference leak without UAF, repeated release, arbitrary write, disclosure, privilege escalation, or direct network reachability. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: netfs: clear PG_private_2 on copy-to-cache append failure [ Upstream Commit: 627826ef4208042b0470d1a3fdb729ce35471a0d Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=627826ef4208042b0470d1a3fdb729ce35471a0d Changed files: fs/netfs/read_pgpriv2.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=627826ef4208042b0470d1a3fdb729ce35471a0d ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80898 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80898 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:L/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: unknown 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).