CVE-2026-23447: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23447 is a bounds-check vulnerability in the Linux kernel's CDC NCM (Communications Device Class Network Control Model) USB driver, specifically in the cdc_ncm_rx_verify_ndp32() function. The flaw allows out-of-bounds reads when the NDP32 (Network Data Packet 32-bit) structure is placed near the end of the NTB (Network Transfer Block), because the DPE array size is validated against the total skb length without accounting for ndpoffset. It affects multiple Linux kernel versions including 4.14.317+, 4.19.285+, 5.4.245+, 5.7 through 6.6.130, 6.7 through 6.12.78, 6.13 through 6.18.20, 6.19 through 6.19.10, and 7.0-rc1 through rc4. The vulnerability was published on April 3, 2026, with a CVSS v3.1 base score of 7.8 (High) (GitHub Advisory, Feedly).

The root cause is classified as CWE-129 (Improper Validation of Array Index). In cdc_ncm_rx_verify_ndp32(), the bounds check for the DPE (Data Packet Element) array computes the required size relative to the start of the socket buffer (skb) without adding ndpoffset — the offset at which the NDP32 structure begins within the NTB. This means that when the NDP32 is positioned near the end of the buffer, the computed bounds can appear valid while the actual DPE array extends beyond the allocated memory, enabling out-of-bounds reads. The fix adds ndpoffset to the nframes bounds check and uses struct_size_t() to express the NDP-plus-DPE-array size more clearly. This is analogous to a previously fixed bug in cdc_ncm_rx_verify_ndp16() (GitHub Advisory, Feedly).

Successful exploitation can result in out-of-bounds reads of kernel memory, potentially disclosing sensitive kernel memory contents to a local attacker. The vulnerability affects confidentiality, integrity, and availability — all rated High in the CVSS scoring — meaning it could also contribute to system instability or be chained with other vulnerabilities for privilege escalation. The attack requires only low privileges and no user interaction, making it a realistic threat in environments where untrusted USB devices or crafted CDC NCM network traffic is possible (Feedly, GitHub Advisory).

Update affected Linux kernel systems to the following patched versions: 6.6.130, 6.12.78, 6.18.20, 6.19.10, or 7.0-rc5 and later (GitHub Advisory, Feedly). SUSE has released security updates (SUSE-SU-2026:2217-1 and SUSE-SU-2026:2238-1) and openSUSE has issued corresponding advisories. As a workaround for systems that cannot be immediately patched, disable CDC NCM USB driver support (cdc_ncm kernel module) if it is not required for critical functionality, and restrict connections from untrusted USB devices. Kernel patches are available via the stable kernel tree at git.kernel.org.

The Yocto Project security mailing list discussed the vulnerability across multiple messages in April–May 2026, indicating active tracking by embedded Linux communities (Yocto Security List). SUSE issued security advisories and updates for their enterprise Linux products, and Tenable added detection plugins (e.g., plugin 304911) for the vulnerability. No significant public researcher commentary or social media discussion has been identified beyond standard vendor patch tracking.