From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-52986][MODERATE 7.0] netfilter: nf_conntrack_sip: don't use simple_strtoul [ Upstream Date: Thu, 25 Jun 2026 16:14:44 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-52986 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: 6 X-AL-KERNEL-ActionableScore-Lower: 5 X-AL-KERNEL-Commit: 8cd0358379570003659186706e077929d6930c40 List-Id: CVE: CVE-2026-52986 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: netfilter: nf_conntrack_sip: don't use simple_strtoul [ Upstream Commit: 8cd0358379570003659186706e077929d6930c40 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8cd0358379570003659186706e077929d6930c40 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52986 Analysis date: Thu, 25 Jun 2026 16:14:44 -0400 ActionableScore: 6 ActionableScore lower bound: 5 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A remote OOB read and DoS condition exists in the SIP conntrack helper because `simple_strtoul()` parsed non NUL terminated skb data without strict buffer-bound validation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-52986 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52986 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-2026-52986 MODERATE CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-125;*CWE-20;CWE-1284;Other CVSS 'AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '8.6';DESCR 'A remote out of bounds read can occur in the SIP conntrack helper because simple_strtoul() was used on skb data that is not guaranteed to be NUL terminated. Crafted SIP messages can place a port or numeric parameter at the end of the parsed buffer or use very long numeric sequences, causing the parser to read past the validated buffer limit or spend excessive CPU on malformed input. For the CVSS the PR:N is used because an attacker only needs network reachability to traffic processed by nf_conntrack_sip or nf_nat_sip and does not need a local account on the target. The issue is network reachable when the SIP helper is enabled and attacker controlled SIP traffic crosses the firewall or host using this helper. Impact is at least remote denial of service via kernel fault or CPU exhaustion, with limited confidentiality or integrity impact possible from an out of bounds read and parser state confusion. In practice exposure depends on whether SIP conntrack helpers are loaded and assigned to the relevant traffic path, so Internet wide exposure is lower than for a default listening service but internal VoIP or firewall deployments can be affected.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6) MAYBE REMOTE OOB NETFILTER SKB KPANIC PACKET KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=6 ActionableScoreLower=5 ## 1. ActionableScore * Conservative score: **5** * Paranoid score: **6** * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum** ## 2. Signal breakdown * **Remote reachable / network-triggerable: +2** Crafted SIP traffic can trigger the affected parser when `nf_conntrack_sip` or `nf_nat_sip` processes packets. * **Reliable kernel crash / strong DoS: +1** `simple_strtoul()` was used on non NUL terminated skb data, creating an out of bounds read risk and malformed long numeric fields can also cause excessive parser work. * **Common networking core / packet-processing path: +1** This is in netfilter conntrack/NAT packet processing, not a local ioctl or admin-only control path. * **Confidentiality impact plausible: +1** The primitive is primarily a boundedness failure leading to OOB read. There is no clear disclosure channel, so this is limited and conservative. * **Integrity impact plausible in paranoid score: +1** Parser confusion in SIP/NAT parameters may affect conntrack/NAT state, but there is no arbitrary write or strong corruption primitive. This is why it is counted only in the paranoid score. Not counted: * **Generic memory corruption: +0** The patch supports OOB read / parser bounds failure, not UAF, double free, OOB write, heap overwrite, or arbitrary write. * **Privilege escalation plausible: +0** No credible LPE primitive is shown. * **Rare configuration penalty: 0** SIP helpers are configuration-dependent, but this remains netfilter packet-path code and should not be auto-downgraded as rare hardware or obscure debug functionality. ## 3. Reachability analysis A remote attacker can trigger this if attacker-controlled SIP traffic is processed by the SIP conntrack/NAT helper. No local account is required on the target in that exposed configuration. The path is not equivalent to a default listening daemon. Many deployments require the SIP helper module to be loaded and assigned to relevant traffic, and automatic helper assignment may be disabled depending on distribution and configuration. Exposure is therefore common in VoIP/firewall/NAT environments but not universal. Namespaces or containers do not meaningfully reduce the remote-trigger case. Local CAP_NET_ADMIN may be needed to configure the helper, but the attacker only needs packet reachability once the helper is active. ## 4. Severity interpretation This is above ordinary Moderate because it is a remotely reachable netfilter parser bug with an OOB read / strong DoS profile. It does not look like an Important-class memory corruption bug by itself because there is no UAF, overwrite, reclaim primitive, or demonstrated privilege escalation path. Conservatively it is an **Actionable Moderate**. In exposed SIP-helper deployments, the paranoid score makes it a **Strong Important candidate for manual review**, mainly due to remote packet reachability in kernel parser code. ## 5. One-sentence report phrase A remote OOB read and DoS condition exists in the SIP conntrack helper because `simple_strtoul()` parsed non NUL terminated skb data without strict buffer-bound validation. ## 6. Manual review recommendation **MANUAL CHECK REQUIRED** Reason: this is network-reachable netfilter parser code with an OOB read primitive and realistic remote DoS potential when the SIP helper is enabled. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: netfilter: nf_conntrack_sip: don't use simple_strtoul [ Upstream Commit: 8cd0358379570003659186706e077929d6930c40 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8cd0358379570003659186706e077929d6930c40 Changed files: net/netfilter/nf_conntrack_sip.c net/netfilter/nf_nat_sip.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=8cd0358379570003659186706e077929d6930c40 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-52986 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52986 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:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 8.6 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: 5 Paranoid ActionableScore: 6 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).