From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68184][MODERATE REGULAR] cdrom: fix stack out-of-bounds read in CDROMVOLCTRL Date: Mon, 10 Aug 2026 16:55:44 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68184 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: 7344c84e32413e5c8832f74b8a612b0194e5c051 List-Id: CVE: CVE-2026-68184 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: cdrom: fix stack out-of-bounds read in CDROMVOLCTRL Commit: 7344c84e32413e5c8832f74b8a612b0194e5c051 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7344c84e32413e5c8832f74b8a612b0194e5c051 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68184 Analysis date: Mon, 10 Aug 2026 16:55:44 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Ordinary Moderate / Low-like with manual-review sensitivity for kernel stack disclosure Manual review required: NO Summary: A stack out-of-bounds read in CDROMVOLCTRL can send a small amount of adjacent kernel stack data to a CD-ROM device when a non-zero block descriptor causes cgc buffer to be advanced without reducing cgc buflen. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68184 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68184 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 REGULAR 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-2026-68184 MODERATE 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:L';CWE-126;CWE-125;*CWE-200;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '3.6';DESCR 'A stack out-of-bounds read in the CDROMVOLCTRL path can occur because mmc_ioctl_cdrom_volume moves cgc buffer forward to build a MODE SELECT payload but does not reduce cgc buflen by the same amount. When a drive reports a non-zero block descriptor length, cdrom_mode_select may read beyond the 32 byte stack buffer and send extra kernel stack bytes to the CDROM device as part of the outgoing payload. For the CVSS the PR:L is used because a local user or process needs access to the cdrom ioctl path and a suitable device condition is required. The issue is not network reachable. Impact is mainly limited confidentiality exposure to the device side, with only low availability impact in hardened or debug configurations.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like with manual-review sensitivity for kernel stack disclosure (with actual score 3) YES WRITE OOB HARDWARE PACKET DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 ## 1. ActionableScore * Conservative score: 2 * Paranoid score: 3 * Final recommended bucket: **Ordinary Moderate / Low-like with manual-review sensitivity for kernel stack disclosure**:: ## 2. Signal breakdown Conservative signals: * Local unprivileged or low-privileged trigger: +1 A local process with access to the CD-ROM device ioctl path can call CDROMVOLCTRL. * Firmware-mediated external influence: +1 The bug depends on a drive reporting a non-zero block descriptor length, and the overread bytes are sent back to the device as MODE SELECT payload. * Confidentiality impact plausible: +1 The primitive is a small stack out-of-bounds read, potentially exposing adjacent kernel stack bytes to the device side. * Rare or difficult-to-reach hardware condition: -1 It requires a CD-ROM style device path and a device behavior that returns a block descriptor for this mode page. Paranoid adjustment: * Availability impact low but possible: +1 In hardened or debug configurations, stack OOB reads or abnormal packet payloads could produce warnings or failures, but this is not the main demonstrated impact. Not counted: * No generic strong memory corruption. This is a read past a stack buffer, not an OOB write, UAF, double free, type confusion, or arbitrary write. * No privilege escalation signal. The patch does not show attacker-controlled overwrite, reclaim, callback control, or object confusion. * No network reachability. The affected path is a local CD-ROM ioctl path. ## 3. Reachability analysis The realistic trigger is local access to a CD-ROM block device and the CDROMVOLCTRL ioctl path. In normal desktop or server deployments this usually depends on device-node permissions, group membership, udev policy, or a process already allowed to access optical media devices. Containers normally do not receive direct access to such device nodes unless explicitly passed through. The device behavior matters. The issue is only triggered when the drive returns a non-zero block descriptor length, and the leaked bytes are sent as extra MODE SELECT payload to the device. This makes a malicious or observable virtual or physical device more relevant than a pure local-only attacker who cannot inspect device-side traffic. ## 4. Severity interpretation This behaves like a low-end Moderate information disclosure bug, not an Important kernel memory corruption issue. The theoretical concern is kernel stack disclosure, but the amount appears small and the disclosure sink is the CD-ROM device side, not directly normal userspace. There is no evidence of write corruption, LPE, persistent damage, or remote attack surface. The paranoid score is raised only to preserve manual-review sensitivity for kernel stack OOB reads, especially where a virtual or malicious device could observe the MODE SELECT payload. ## 5. One-sentence report phrase A stack out-of-bounds read in CDROMVOLCTRL can send a small amount of adjacent kernel stack data to a CD-ROM device when a non-zero block descriptor causes cgc buffer to be advanced without reducing cgc buflen. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Manual review is recommended because this is a kernel stack out-of-bounds read with a plausible information disclosure path to the device side. It should not be treated as Important without additional evidence of a broader disclosure primitive, attacker-visible readback, memory corruption, or privilege escalation. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: cdrom: fix stack out-of-bounds read in CDROMVOLCTRL Commit: 7344c84e32413e5c8832f74b8a612b0194e5c051 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7344c84e32413e5c8832f74b8a612b0194e5c051 Commit description: mmc_ioctl_cdrom_volume() first reads the audio control mode page into a 32-byte stack buffer with cgc->buflen set to 24. If the device reports a block descriptor, the function increases cgc->buflen to include that descriptor and reads the page again. For CDROMVOLCTRL, the function then builds a MODE SELECT parameter list by moving cgc->buffer forward by offset - 8 bytes. This drops the block descriptor from the outgoing payload and leaves a new 8-byte mode parameter header in front of the audio control page. However, cgc->buflen is left unchanged. With a standard 8-byte block descriptor, cgc->buffer points at buffer + 8 but cgc->buflen remains 32. cdrom_mode_select() therefore asks the low level packet path to write 32 bytes from that adjusted pointer, reading 8 bytes past the end of the 32-byte stack buffer. This is not hit by CDROMVOLREAD, and CDROMVOLCTRL only triggers it on drives that return a non-zero block descriptor length, which helps explain why it has gone unnoticed. The overread is also sent to the device as extra MODE SELECT payload, so it may not produce an obvious local failure. Reduce cgc->buflen by the same amount as the buffer pointer adjustment so the MODE SELECT transfer covers only the intended parameter list. Fixes: 1da177e ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Xu Rao Signed-off-by: Phillip Potter Link: https://patch.msgid.link/20260720194421.1497-2-phil@philpotter.co.uk Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman Changed files: drivers/cdrom/cdrom.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=7344c84e32413e5c8832f74b8a612b0194e5c051 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68184 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68184 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:L/I:N/A:N The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L The Best / paranoid CVSS score: 3.6 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: 2 Paranoid ActionableScore: 3 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: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).