From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97590][MODERATE REGULAR] s390/crypto: Fix missing scrub of temp buffers with PAES algorithm Date: Fri, 25 Sep 2026 07:14:17 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97590 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 7d1456d54b3c784cc2917c219a528092cefe30cd List-Id: CVE: CVE-2026-97590 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: s390/crypto: Fix missing scrub of temp buffers with PAES algorithm Commit: 7d1456d54b3c784cc2917c219a528092cefe30cd Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d1456d54b3c784cc2917c219a528092cefe30cd Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97590 Analysis date: Fri, 25 Sep 2026 07:14:17 -0400 ActionableScore: 0 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-2026-97590 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97590 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: MODERATE REGULAR 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-2026-97590 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-97590 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:H/I:N/A:N';CWE-226;*CWE-200;CWE-212;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '4.7';DESCR 'The s390 PAES implementation did not fully scrub temporary buffers after cryptographic operations. ctr_paes_do_crypt() could leave data from a partial AES block in a local buffer, while __xts_2keys_prep_param() cleared only the key field instead of the complete temporary parameter block. Residual plaintext, ciphertext, key related data, or other cryptographic parameters could remain in reusable memory. Exploitation requires an additional mechanism that exposes the stale contents, so the bug does not by itself provide a direct arbitrary read primitive. For the CVSS the PR:L reflects that a local user or process is required to invoke an accessible cryptographic path and obtain residual data through a secondary disclosure channel. The issue is not directly network reachable. Impact is limited to confidentiality, but disclosure could be significant if the retained bytes contain protected key material or sensitive intermediate state.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) SKIP CVE-2026-97590 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE SIMPLEFIX HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 0. * Conservative score: 0. * Raw paranoid score: 0. * Paranoid score: 0. * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +0 Residual sensitive data. The patch establishes incomplete scrubbing of temporary PAES buffers, but the scoring rules provide no bonus without a concrete disclosure path. * +0 Confidentiality plausible was not awarded. No read-back, copy-to-userspace, network output, or other mechanism exposing the residual bytes is established. * +0 Local unprivileged trigger was not awarded. A userspace path that both invokes PAES and observes the residual data is not supplied. * +0 Strong or weak corruption was not awarded. There is no UAF, OOB access, overwrite, stale object, or lifetime violation. * +0 Availability and integrity were not awarded. No crash, state modification, or denial of service is established. * +0 Remote reachability was not awarded. The affected operation is an architecture-specific local cryptographic implementation. * Controlled reclaim, arbitrary read or write, authorization bypass, privilege escalation, and a practical exploit chain are not demonstrated. * The supplied paranoid CVSS confidentiality rating does not independently establish an ActionableScore confidentiality signal. 3. Reachability analysis The vulnerable PAES operations run on s390 systems using the protected-key AES implementation. A local process may potentially invoke registered crypto algorithms through a kernel consumer or userspace crypto interface, but the supplied context does not establish the complete invocation path or a way to retrieve the residual stack contents. Host-admin privilege is therefore unresolved rather than positively required or positively unnecessary. No namespace-scoped capability chain is identified. There is no network trigger, race, boot option, or synchronization condition. The architecture and PAES dependency limit deployment exposure, but no rarity penalty is applied because architecture-specific placement alone is insufficient. 4. Primitive and severity interpretation The exact defect is incomplete erasure of temporary cryptographic state. `ctr_paes_do_crypt()` leaves its partial-block buffer uncleared, and `__xts_2keys_prep_param()` clears only the key field rather than the complete temporary parameter block. This is not a UAF or memory-corruption primitive. The retained data may include plaintext, ciphertext, key-related material, or intermediate parameters, but no independent mechanism for reading that memory is shown. The issue is therefore PrimitiveClass NONE rather than a substantial disclosure primitive. The demonstrated consequence is residual sensitive data in reusable memory. Actual confidentiality loss remains speculative pending identification of a secondary exposure path. ImportantCandidate is NO because no direct disclosure, corruption, boundary bypass, or privilege-escalation mechanism is established. AutoDowngradeAllowed is YES because no unresolved Important-grade primitive exists. Operational severity is Low-like or ordinary Moderate, although crypto-sensitive context merits targeted review. 5. One-sentence report phrase The s390 PAES implementation failed to scrub complete temporary cryptographic buffers, potentially leaving sensitive residual data in reusable memory, but no direct disclosure path is established. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Review callers and stack reuse paths to determine whether residual PAES data can be copied to userspace, another request, a device-visible buffer, logs, or crash output. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: s390/crypto: Fix missing scrub of temp buffers with PAES algorithm Commit: 7d1456d54b3c784cc2917c219a528092cefe30cd Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d1456d54b3c784cc2917c219a528092cefe30cd Commit description: In function ctr_paes_do_crypt() there is a buffer used to process remaining bytes < AES_BLOCK_SIZE. This buffer was not scrubbed and thus could lead to expose of unwanted data. Rework the code to explicitly scrub the buffer at the end of the function to avoid exposure of maybe sensitive data. In function __xts_2keys_prep_param() change the existing scrub to clean the whole param block instead of just the key field. Fixes: 6cd87cb ("s390/crypto: Rework protected key AES for true asynch support") Signed-off-by: Harald Freudenberger Reviewed-by: Holger Dengler Cc: stable@vger.kernel.org # 6.16+ Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman Changed files: arch/s390/crypto/paes_s390.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=7d1456d54b3c784cc2917c219a528092cefe30cd ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97590 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97590 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:L/I:N/A:N The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N 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: 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: MODERATE KPANIC detected for this report: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).