CVE-2026-43081 Overview
CVE-2026-43081 is a Linux kernel defect in the IP Accelerator (IPA) networking driver. The flaw resides in the net: ipa driver code path that handles the GENERIC_CMD register for IPA hardware version 5.0 and later. The field masks used by the driver did not match the hardware layout documented in the downstream Generic Software Interface (GSI) reference (GSI_V3_0_EE_n_GSI_EE_GENERIC_CMD_*). The mismatch surfaced as a kernel WARN when issuing a stop command to the Modem Peripheral Subsystem (MPSS) remoteproc while IPA was active.
Critical Impact
Incorrect register field masks in the IPA v5.0+ driver trigger kernel warnings and can disrupt orderly shutdown of the modem remoteproc on affected Qualcomm-based Linux platforms.
Affected Products
- Linux kernel net/ipa driver on platforms using IPA hardware v5.0 or later
- Qualcomm-based systems where IPA interacts with the MPSS remoteproc subsystem
- Stable kernel branches referenced by commits 2aa50d2, 9709b56, a7d326d, bafc45e, and d1c6639
Discovery Timeline
- 2026-05-06 - CVE-2026-43081 published to the National Vulnerability Database (NVD)
- 2026-05-06 - Last updated in NVD database
Technical Details for CVE-2026-43081
Vulnerability Analysis
The Linux IPA driver programs the GENERIC_CMD register to coordinate generic commands between the Application Processor and the GSI hardware that fronts the IPA. Each command field, including the opcode, endpoint identifier, and parameters, is encoded into specific bit ranges of the register. For IPA versions 5.0 and later, the bit layout changed compared to earlier hardware revisions. The driver retained masks aligned with the older layout, so the encoded command did not land in the bit positions the hardware expected.
When the kernel issued a stop command to the MPSS remoteproc while IPA was up, the malformed GENERIC_CMD triggered a WARN in the IPA control path. The defect is a kernel driver correctness issue [CWE-1384-class] rather than a memory safety vulnerability, but it produces noisy kernel logs and impedes graceful modem teardown on affected SoCs.
Root Cause
The root cause is incorrect bitfield mask constants in the IPA driver for the GENERIC_CMD register on IPA v5.0+. The masks did not match the hardware layout described in the downstream GSI_V3_0_EE_n_GSI_EE_GENERIC_CMD_* register definitions. Commands written under the old layout were misinterpreted by GSI on newer hardware.
Attack Vector
This is a local kernel correctness defect, not a remotely exploitable flaw. It is reached during normal modem lifecycle operations such as stopping the MPSS remoteproc while IPA is active. There is no public exploit, no CISA Known Exploited Vulnerabilities listing, and the EPSS score is 0.018%. The fix replaces the field masks with values matching the GSI v3.0 hardware layout. See the upstream commits referenced below for the exact mask values and code paths involved.
Detection Methods for CVE-2026-43081
Indicators of Compromise
- Kernel WARN or backtraces originating in the drivers/net/ipa/ source tree, particularly around GENERIC_CMD handling
- dmesg entries correlated with rprocstop operations against the MPSS remoteproc while IPA is up
- Failed or stalled modem teardown on Qualcomm SoCs running IPA v5.0+ kernels without the fix
Detection Strategies
- Inventory Linux kernel builds across mobile, embedded, and edge devices and identify those using the ipa driver on IPA v5.0+ hardware
- Compare in-tree commit hashes against the fixed commits 2aa50d2c1f63, 9709b56d908a, a7d326dfb13b, bafc45ea30d2, and d1c66396796f
- Collect kernel logs centrally and search for WARN_ON traces referencing IPA or GSI command paths
Monitoring Recommendations
- Forward dmesg and journalctl -k output from production endpoints into a centralized log pipeline for trend analysis
- Alert on repeated kernel warnings tied to remoteproc state transitions, which can indicate driver-firmware desynchronization
- Track kernel version and patch level as configuration data to drive vulnerability remediation reporting
How to Mitigate CVE-2026-43081
Immediate Actions Required
- Apply the upstream Linux kernel patch series that corrects the GENERIC_CMD field masks for IPA v5.0+
- Rebuild and redeploy kernels for any device images that include the ipa driver on affected Qualcomm SoCs
- Validate modem start and stop sequences after patching to confirm the WARN no longer fires
Patch Information
The fix is available in the upstream Linux kernel via the following commits: Linux Kernel Commit 2aa50d2, Linux Kernel Commit 9709b56, Linux Kernel Commit a7d326d, Linux Kernel Commit bafc45e, and Linux Kernel Commit d1c6639. Backports are present across the supported stable trees.
Workarounds
- Avoid issuing stop to the MPSS remoteproc while IPA is up on unpatched kernels to suppress the WARN condition
- Pin device images to kernel branches that already include the corrected GENERIC_CMD masks until full upgrades roll out
- Track downstream vendor advisories from SoC and device manufacturers for integration of the fix into BSP releases
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
