From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97592][LOW] s390/crypto: Fix missing scrub of temp buffers with AES ctr and gcm algorithm Date: Fri, 25 Sep 2026 08:32:08 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97592 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: 11eca05d2062032e1f07d56be58ed0b99f4b1d63 List-Id: CVE: CVE-2026-97592 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: s390/crypto: Fix missing scrub of temp buffers with AES ctr and gcm algorithm Commit: 11eca05d2062032e1f07d56be58ed0b99f4b1d63 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=11eca05d2062032e1f07d56be58ed0b99f4b1d63 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97592 Analysis date: Fri, 25 Sep 2026 08:32:08 -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-2026-97592 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97592 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-2026-97592 LOW https://www.kernelcve.org/list/?q=CVE-2026-97592 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:L/I:N/A:N';CWE-226;*CWE-200;CWE-459;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:N';BEST CVSS score: '2.5';DESCR 'Temporary buffers in the s390 AES CTR and GCM implementations were not explicitly cleared after use and on selected GCM error paths. Residual data may include partial plaintext, cryptographic intermediate values, or parameter block contents, but the patch does not show a direct kernel memory disclosure primitive or a way for an attacker to read the residual stack data. For the CVSS the PR:L value is used for the conservative scenario because a local process must invoke a relevant crypto path, for example through an available crypto API interface. The issue is not network reachable by itself. Impact is not a direct denial of service or privilege escalation. A limited confidentiality impact is only plausible when combined with a separate kernel memory disclosure weakness. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES NOMEMCHK SIMPLEFIX ERRORPATH HARDWARE LINUS YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 0 * Conservative score: 0 * Raw paranoid score: 0 * Paranoid score: 0 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap applies. The patch improves sensitive-data hygiene, but it does not establish a direct disclosure, corruption, lifetime, authorization, or availability primitive. 2. Signal breakdown * +0 Residual sensitive data: `ctr_aes_crypt()` leaves a temporary stack buffer uncleared, and selected `gcm_aes_crypt()` error paths previously bypassed cleanup of `param`, `gw_in.buf`, and `gw_out.buf`. This is a concrete cleanup deficiency, but no score is added because the supplied patch does not establish a read-back path. * +0 Confidentiality impact not awarded: no bytes are copied to userspace, transmitted, logged, exposed through an ioctl, or otherwise made observable after the function returns. * +0 Integrity impact not awarded: the patch does not establish an attacker-controlled write, altered cryptographic result, ownership violation, or policy bypass. * +0 Availability impact not awarded: no crash, allocation exhaustion, lockup, or service failure is described. * +0 Local-unprivileged trigger not awarded: a possible crypto API or AF_ALG path is insufficient to prove that an ordinary user can trigger the complete relevant s390 implementation and separately recover residual kernel-stack data. * +0 No remote reachability: the AES CTR and GCM implementation is not directly network reachable by itself. * +0 No memory corruption: there is no UAF, OOB access, double free, refcount error, stale pointer, or invalid object lifetime operation. * +0 No exploit-chain point: obtaining useful data would require a separate kernel memory disclosure, crash dump access, or comparable independent weakness. That separate weakness is not part of this CVE. 3. Reachability analysis The affected code is the s390 hardware-assisted AES CTR and GCM crypto implementation. A local kernel client, or potentially a local userspace crypto consumer through an available crypto interface, may cause these functions to process cryptographic requests. However, the complete security-relevant operation is not merely invoking encryption. An attacker would also need a separate way to recover the residual contents of kernel stack or temporary kernel memory after the function returns. No such recovery mechanism is established by the patch or supplied context. Host-admin-equivalent privilege is not positively established, but below-host-admin exploitation is also not established because the complete trigger-and-disclosure chain is missing. Therefore `HostAdminRequired=UNKNOWN`. No namespace-scoped capability analysis is applicable from the supplied evidence. `NamespaceScopedPrivilege=UNKNOWN`. The implementation requires s390 architecture and the relevant s390 crypto support. This is architecture-specific, but no negative score is applied because the absence of a demonstrated disclosure primitive is already decisive. 4. Primitive and severity interpretation The exact defect is failure to explicitly clear temporary cryptographic buffers after use or on selected GCM error exits. `ctr_aes_crypt()` processes a partial AES block through a local temporary `buf`. Before the fix, that buffer could retain processed data after the function completed. In `gcm_aes_crypt()`, selected error paths returned before clearing the CPACF parameter block and the GCM scatter-gather walk buffers. This is not an active structured-object lifetime issue, fixed stale storage issue, UAF, refcount defect, OOB primitive, or authorization bypass. It is a residual-sensitive-data cleanup issue. The demonstrated consequence is only that potentially sensitive temporary data can remain in kernel memory longer than intended. The speculative consequence is limited disclosure if a separate and independent kernel-memory disclosure primitive, debug facility, crash-dump access path, or other read-back mechanism exists. `PrimitiveClass=NONE` is appropriate because no meaningful attacker-usable corruption, lifetime, ownership, authorization, or disclosure primitive is directly established. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because there is no unresolved concrete exploitation mechanism beyond a separate unrelated information-disclosure flaw. Likely operational severity is low security hygiene impact. Patch application remains advisable because explicit clearing of cryptographic intermediates is defense in depth and reduces exposure if another kernel disclosure condition exists. 5. One-sentence report phrase The s390 AES CTR and GCM implementations did not scrub selected temporary cryptographic buffers after use or on error paths, but no direct information disclosure, memory corruption, privilege escalation, or denial of service primitive is established. 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch fixes residual sensitive-data cleanup only. No direct attacker-visible disclosure path or kernel corruption primitive is present in the supplied evidence. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: s390/crypto: Fix missing scrub of temp buffers with AES ctr and gcm algorithm Commit: 11eca05d2062032e1f07d56be58ed0b99f4b1d63 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=11eca05d2062032e1f07d56be58ed0b99f4b1d63 Commit description: In function ctr_aes_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. When the buffer is used explicitly scrub it at the end of the code block to avoid exposure of maybe sensitive data. In a similar way the function gcm_aes_crypt() hat an error path where the CPACF param block was not scrubbed. Instead of return early now these error paths go to end of function where explicit scrubbing is done. Similar with the buffers which are part of the gcm_sg_walk structs from the variables gw_in and gw_out. Fixes: d07f951 ("crypto: s390/aes - Fix buffer overread in CTR mode") Signed-off-by: Harald Freudenberger Reviewed-by: Holger Dengler Cc: stable@vger.kernel.org # 6.8+ Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman Changed files: arch/s390/crypto/aes_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=11eca05d2062032e1f07d56be58ed0b99f4b1d63 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97592 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97592 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:N The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N The Best / paranoid CVSS score: 2.5 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).