From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99220][LOW] asymmetric_keys: reject trust keys without IDs Date: Mon, 02 Nov 2026 22:46:15 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99220 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: 889a2293a95f6c2880bf73b67f9b0af23251a128 List-Id: CVE: CVE-2026-99220 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: asymmetric_keys: reject trust keys without IDs Commit: 889a2293a95f6c2880bf73b67f9b0af23251a128 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=889a2293a95f6c2880bf73b67f9b0af23251a128 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99220 Analysis date: Mon, 02 Nov 2026 22:46:15 -0400 ActionableScore: 2 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: An unprivileged local caller can supply a PKCS#8 trust key without key IDs and trigger a NULL-pointer dereference and kernel panic during keyring restriction enforcement. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99220 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99220 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-2026-99220 LOW https://www.kernelcve.org/list/?q=CVE-2026-99220 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;*CWE-20;BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference in key_or_keyring_common occurs when a PKCS8 private key lacking asymmetric key IDs is used as a trust key for a key_or_keyring restriction. An unprivileged local caller can reach the vulnerable path through KEYCTL_RESTRICT_KEYRING followed by add_key and can cause a kernel panic. For the CVSS the PR:L value is selected because local user context and permission to operate on an attacker controlled keyring are required. The demonstrated primitive is a NULL pointer dereference with availability impact only and there is no supported UAF OOB access information leak or controlled write primitive. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to LOW because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 4.9 and ActionableScore 2 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE KASAN OOB NULLPTR LEAK HARDWARE LINUS V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 2. * Conservative score: 2; no floor or cap applied. * Raw paranoid score: 2. * Paranoid score: 2; no technically supported stronger primitive. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Local unprivileged trigger: the supplied call path establishes attacker-controlled keyring operations through `KEYCTL_RESTRICT_KEYRING` followed by `add_key()`. * +1 Reliable kernel crash/strong DoS: unconditional dereference of a NULL `asymmetric_key_ids` pointer produced a demonstrated fatal exception and kernel panic. * No extra availability point: the panic is the same effect already counted. * No corruption bonus: this is a NULL-pointer read/dereference, not a heap OOB write, UAF, controlled write, or corrupted active state. * No authorization-bypass score: the new `kids` check rejects an invalid trust-anchor representation; it does not restore a missing capability or convert an authorization DENY into ALLOW. * No confidentiality, integrity, protected-resource, or LPE effect is shown. 3. Reachability analysis An ordinary local user can create and operate on an attacker-controlled keyring and supply the PKCS#8 key needed for the demonstrated syscall sequence. Host UID 0, host-administrator capability, namespace capability, prior privileged setup, special hardware, and a race are not required by the supplied evidence. Remote reachability is not shown. 4. Primitive and severity reading The exact primitive is a deterministic NULL-pointer dereference when `asymmetric_key_ids(trusted)` returns NULL and the old code immediately accesses `->id`. This is CLASS_C crash/DoS behavior, not a lifetime violation or useful memory-corruption primitive. The patch-supported effect is an unprivileged host kernel panic; stronger C/I effects are unsupported. ImportantCandidate is NO and automatic Important-to-Moderate downgrade is allowed because no unresolved corrupt, ownership, lifetime, or authorization primitive remains. 5. One-sentence report phrase An unprivileged local caller can supply a PKCS#8 trust key without key IDs and trigger a NULL-pointer dereference and kernel panic during keyring restriction enforcement. 6. Manual review advice MANUAL CHECK RECOMMENDED Confirm product keyring availability and panic-on-Oops behavior, but no Important-preserving primitive is shown. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: asymmetric_keys: reject trust keys without IDs Commit: 889a2293a95f6c2880bf73b67f9b0af23251a128 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=889a2293a95f6c2880bf73b67f9b0af23251a128 Commit description: The PKCS#8 parser deliberately leaves the asym_key_ids payload slot empty. key_or_keyring_common() unconditionally dereferences that slot when a PKCS#8 key is supplied to a key_or_keyring restriction. Both the plain and :chain forms reach this branch, allowing an unprivileged caller to trigger a NULL pointer dereference through KEYCTL_RESTRICT_KEYRING followed by add_key(). Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000 KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:key_or_keyring_common (crypto/asymmetric_keys/restrict.c:205 crypto/asymmetric_keys/restrict.c:279) Call Trace: __key_create_or_update (security/keys/key.c:884) key_create_or_update (security/keys/key.c:1021) __do_sys_add_key (security/keys/keyctl.c:134) do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Kernel panic - not syncing: Fatal exception Reject an asymmetric restriction key without key IDs. A PKCS#8 private key cannot identify the signer of a candidate certificate and is not a valid trust anchor. Fixes: 3c58b23 ("KEYS: Implement PKCS#8 RSA Private Key parser [ver #2]") Cc: stable@vger.kernel.org Reported-by: Xiang Mei Link: https://lore.kernel.org/r/20260429181629.110802-2-bestswngs@gmail.com Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman Changed files: crypto/asymmetric_keys/restrict.c security/keys/key.c security/keys/keyctl.c arch/x86/entry/common.c arch/x86/entry/entry_64.S 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=889a2293a95f6c2880bf73b67f9b0af23251a128 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99220 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99220 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: Not available The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.5 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: 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).