CVE-2025-21742: linux kernel Out-of-bounds Read — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: usbnet: ipheth: use static NDP16 location in URB Original code allowed for the start of NDP16 to be anywhere within the URB based on the `wNdpIndex` value in NTH16. Only the start position of NDP16 was checked, so it was possible for even the fixed-length part of NDP16 to extend past the end of URB, leading to an out-of-bounds read. On iOS devices, the NDP16 header always directly follows NTH16. Rely on and check for this specific format. This, along with NCM-specific minimal URB length check that already exists, will ensure that the fixed-length part of NDP16 plus a set amount of DPEs fit within the URB. Note that this commit alone does not fully address the OoB read. The limit on the amount of DPEs needs to be enforced separately.

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CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.5 — 6.6.78
linux	linux_kernel	6.7 — 6.12.14
linux	linux_kernel	6.13 — 6.13.3

References

Advisories & Patches

https://git.kernel.org/stable/c/2b619445dcb6dab97d8ed033fb57225aca1288c4 https://git.kernel.org/stable/c/86586dcb75cb8fd062a518aca8ee667938b91efb https://git.kernel.org/stable/c/8fb062178e1ce180e2cfdc9abc83a1b9fea381ca https://git.kernel.org/stable/c/cf1ac7f7cf601ac31d1580559c002b5e37b733b7

Frequently Asked Questions

What is CVE-2025-21742? +

In the Linux kernel, the following vulnerability has been resolved: usbnet: ipheth: use static NDP16 location in URB Original code allowed for the start of NDP16 to be anywhere within the URB based on the `wNdpIndex` value in NTH16. Only the start position of NDP16 was checked, so it was possible for even the fixed-length part of NDP16 to extend past the end of URB, leading to an out-of-bounds read. On iOS devices, the NDP16 header always directly follows NTH16. Rely on and check for this specific format. This, along with NCM-specific minimal URB length check that already exists, will ensure that the fixed-length part of NDP16 plus a set amount of DPEs fit within the URB. Note that this commit alone does not fully address the OoB read. The limit on the amount of DPEs needs to be enforced separately. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2025-21742? +

CVE-2025-21742 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-21742? +

CVE-2025-21742 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21742? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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