From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-63805][MODERATE 7.0] crypto: nx - fix nx_crypto_ctx_exit argument Date: Sun, 19 Jul 2026 10:58:24 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-63805 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: 8d8507a457667f23477a15496b91908a5b5b7cf3 List-Id: CVE: CVE-2026-63805 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: crypto: nx - fix nx_crypto_ctx_exit argument Commit: 8d8507a457667f23477a15496b91908a5b5b7cf3 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8d8507a457667f23477a15496b91908a5b5b7cf3 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63805 Analysis date: Sun, 19 Jul 2026 10:58:24 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: A local AF_ALG user can trigger a type confusion in the crypto nx context cleanup path during Crypto API object destruction, causing a kernel oops and raising a weak but review-worthy memory corruption concern. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63805 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63805 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 7.0 Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-63805 MODERATE 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:H/I:H/A:H';CWE-843;CWE-763;**CWE-476;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A type confusion in the crypto nx context cleanup path can occur because nx_crypto_ctx_exit() treated an nx_crypto_ctx pointer as a crypto_tfm pointer and then derived a bogus context with crypto_tfm_ctx(). This can make the driver free or access memory through an invalid kernel pointer during Crypto API object destruction, producing an oops when AF_ALG userspace closes the affected transform. For the CVSS the PR:L is used because a local user or local process is needed to create and release the AF_ALG crypto object, but full administrative privileges are not necessarily required. The issue is not network reachable by itself and depends on the nx crypto driver and affected algorithms being available on the system. Impact is at least local denial of service via kernel crash. In the paranoid interpretation, the bug class is type confusion with invalid free or wrong object access, so memory corruption and privilege escalation risk should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) YES DANGER INIT LINUS KPANIC YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Local unprivileged trigger: +1. The observed call trace comes from AF_ALG release from userspace, and AF_ALG crypto sockets are commonly reachable by local unprivileged processes unless restricted by policy. * Memory corruption, weak/indirect corruption candidate: +1. The bug is a type confusion / bogus struct interpretation where an nx_crypto_ctx pointer is treated as crypto_tfm and then passed through crypto_tfm_ctx(). * Reliable kernel crash / strong DoS: +1. The commit includes a real kernel oops from bad kernel memory access during crypto object destruction. * Local unprivileged high-control kernel data-plane API refinement: +1. AF_ALG lets local users create and destroy Crypto API objects and influence transform lifetime paths. Paranoid additional signal: * Weak LPE concern: +1. The cleanup path can operate on a bogus derived context and may call kfree_sensitive() and write NULL through fields of an incorrectly interpreted object. This is not a demonstrated exploit primitive, but it is more serious than a plain NULL dereference. Negative / limiting factors: * Hardware / configuration dependency: -1 considered for conservative interpretation. The affected nx crypto driver depends on specific hardware / driver availability and affected algorithms being exposed. * No remote reachability: 0. This is not network-triggerable by itself. * No strong LPE primitive: 0. The patch does not show attacker-controlled reclaim, controlled overwrite, callback control, or arbitrary write. ## 3. Reachability analysis A local process can potentially trigger the bug by creating and releasing AF_ALG crypto objects that use the affected nx backend. The trace shows the failure during socket close and Crypto API transform destruction, so this is a local userspace reachable lifetime / cleanup path rather than a privileged driver initialization path. Namespaces and containers can matter because AF_ALG may be available inside containers unless blocked by seccomp, LSM, or container runtime policy. This does not require full host root in the generic Linux model, but practical reachability depends on whether the nx algorithms are registered and visible to the attacker. The path is not remotely reachable unless an application exposes an AF_ALG-backed crypto operation to remote input and performs object creation / teardown on behalf of the attacker, which is not inherent to the kernel bug. Call-site confidence: medium. The provided trace shows the relevant destruction path through AF_ALG and Crypto API, but the full set of nx shash / skcipher callers is not included. ## 4. Severity interpretation This behaves above an ordinary Moderate because it is not just validation or a warning. It is a real type confusion in a cleanup path with an observed kernel oops and possible wrong-object cleanup. Realistic impact is local denial of service on systems with the affected nx crypto backend available. Theoretical impact includes memory corruption concerns because the wrong context can be used for freeing sensitive memory and clearing fields, but the patch does not demonstrate a controlled overwrite, UAF reclaim, or reliable privilege escalation path. Therefore, conservative handling is Borderline / manual review recommended, while paranoid handling reaches Actionable Moderate and should not be auto-closed without review. ## 5. One-sentence report phrase A local AF_ALG user can trigger a type confusion in the crypto nx context cleanup path during Crypto API object destruction, causing a kernel oops and raising a weak but review-worthy memory corruption concern. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: the bug is a type confusion / wrong-object cleanup issue in a local unprivileged AF_ALG reachable path, with an observed crash and a plausible weak memory corruption concern even though practical privilege escalation is not demonstrated. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: crypto: nx - fix nx_crypto_ctx_exit argument Commit: 8d8507a457667f23477a15496b91908a5b5b7cf3 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8d8507a457667f23477a15496b91908a5b5b7cf3 Commit description: nx_crypto_ctx_shash_exit calls nx_crypto_ctx_exit with crypto_shash_ctx(...) but crypto_shash_ctx gives a nx_crypto_ctx *, not a crypto_tfm *. Fix the type in nx_crypto_ctx_exit and drop the bogus crypto_tfm_ctx call. This fixes the following oops: BUG: Unable to handle kernel data access at 0xc0403effffffffc8 Faulting instruction address: 0xc000000000396cb4 Oops: Kernel access of bad area, sig: 11 [#15] Call Trace: nx_crypto_ctx_shash_exit+0x24/0x60 crypto_shash_exit_tfm+0x28/0x40 crypto_destroy_tfm+0x98/0x140 crypto_exit_ahash_using_shash+0x20/0x40 crypto_destroy_tfm+0x98/0x140 hash_release+0x1c/0x30 alg_sock_destruct+0x38/0x60 __sk_destruct+0x48/0x2b0 af_alg_release+0x58/0xb0 __sock_release+0x68/0x150 sock_close+0x20/0x40 __fput+0x110/0x3a0 sys_close+0x48/0xa0 system_call_exception+0x140/0x2d0 system_call_common+0xf4/0x258 .. which came from hardlink(1) opportunistically using AF_ALG. The same problem exists with nx_crypto_ctx_skcipher_exit getting a context it wasn't expecting, but apparently nobody hit that for years. Cc: Eric Biggers Cc: stable@vger.kernel.org Fixes: bfd9efd ("crypto: nx - convert AES-ECB to skcipher API") Fixes: 9420e62 ("crypto: nx - Use API partial block handling") Acked-by: Breno Leitao Reviewed-by: Eric Biggers Reported-by: Calvin Buckley Tested-by: Calvin Buckley Suggested-by: Brad Spengler Signed-off-by: Sam James Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman Changed files: drivers/crypto/nx/nx.c drivers/crypto/nx/nx.h 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=8d8507a457667f23477a15496b91908a5b5b7cf3 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63805 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63805 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:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 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: 4 Paranoid ActionableScore: 5 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: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).