From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-45887][LOW] af_unix: Fix memleak of newsk in unix_stream_connect(). [ Upstream Date: Wed, 27 May 2026 23:03:45 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-45887 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: 1 X-AL-KERNEL-Commit: 365996a2b14d07caa9e33d367b67ea26c09d89b4 List-Id: CVE: CVE-2026-45887 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: af_unix: Fix memleak of newsk in unix_stream_connect(). [ Upstream Commit: 365996a2b14d07caa9e33d367b67ea26c09d89b4 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=365996a2b14d07caa9e33d367b67ea26c09d89b4 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45887 Analysis date: Wed, 27 May 2026 23:03:45 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: An AF_UNIX stream connect error path can leak `newsk` when `prepare_peercred()` fails after socket allocation, creating a local resource-exhaustion risk. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45887 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45887 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-2026-45887 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'An AF_UNIX stream connect error path can leak the newly allocated socket when prepare_peercred() fails after unix_create1() has already created newsk. A local user could theoretically repeat failing AF_UNIX connect attempts and accumulate leaked socket resources, but reliable triggering depends on making prepare_peercred() fail after allocation and is therefore not straightforward. For the CVSS the PR:L is used because the path is reachable from local user context through AF_UNIX sockets, while full administrator privileges are not required. The issue is not network reachable. Impact is limited to availability through resource exhaustion. No supported evidence indicates information disclosure, integrity impact, kernel memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) SKIP CVE-2026-45887 SKIP The Fixes patch not applied yet, so unlikely that actual: fd0a109a0f6b7524543d17520da92a44a9f5343c YES NO NO unknown MAYBE REMOTE SIMPLEFIX LEAK SKB - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown * Local unprivileged trigger: +1 AF_UNIX stream connect is reachable from local user context. * Availability impact realistic: +1 in paranoid scoring Repeated failures could leak socket resources and eventually cause resource exhaustion. * Hard failure condition required: -1 The leak only occurs if `prepare_peercred()` fails after `unix_create1()` allocated `newsk`, which is not a normal deterministic connect path. * No memory corruption: +0 This is a missing cleanup/resource leak, not UAF, double-free, OOB write, or arbitrary write. * No remote reachability: +0 AF_UNIX is local IPC, not network reachable. * No confidentiality or integrity impact: +0 The patch does not indicate data disclosure, policy bypass, or privilege escalation. ## 3. Reachability analysis A local process can reach `unix_stream_connect()`, but reliable exploitation depends on forcing `prepare_peercred()` to fail after `newsk` allocation. That likely requires resource pressure or uncommon failure conditions. Namespaces do not fundamentally change the assessment, though untrusted local tenants can create many AF_UNIX connect attempts. The issue is not network reachable. Realistic exploitation is local resource exhaustion only. ## 4. Severity interpretation This behaves like Low or ordinary Moderate. It is a local resource leak in an uncommon error path. There is no demonstrated memory corruption, no LPE primitive, and no information disclosure. The main practical concern is repeated local attempts causing socket memory/resource pressure. ## 5. One-sentence report phrase An AF_UNIX stream connect error path can leak `newsk` when `prepare_peercred()` fails after socket allocation, creating a local resource-exhaustion risk. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This is a local hard-to-trigger resource leak with no memory corruption, no remote exposure, and no privilege escalation evidence. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: af_unix: Fix memleak of newsk in unix_stream_connect(). [ Upstream Commit: 365996a2b14d07caa9e33d367b67ea26c09d89b4 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=365996a2b14d07caa9e33d367b67ea26c09d89b4 Changed files: net/unix/af_unix.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=365996a2b14d07caa9e33d367b67ea26c09d89b4 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45887 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45887 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:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H 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: 1 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).