CVE-2026-53003 Details
Description
In the Linux kernel, the following vulnerability has been resolved: pppoe: drop PFC frames RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the current PPPoE driver assumes an uncompressed (2-byte) protocol field. However, the generic PPP layer function ppp_input() is not aware of the negotiation result, and still accepts PFC frames. If a peer with a broken implementation or an attacker sends a frame with a compressed (1-byte) protocol field, the subsequent PPP payload is shifted by one byte. This causes the network header to be 4-byte misaligned, which may trigger unaligned access exceptions on some architectures. To reduce the attack surface, drop PPPoE PFC frames. Introduce ppp_skb_is_compressed_proto() helper function to be used in both ppp_generic.c and pppoe.c to avoid open-coding.
A vulnerability in the Linux kernel's PPPoE implementation has been addressed. The issue arises from the generic PPP layer accepting Protocol Field Compression (PFC) frames, despite the current PPPoE driver assuming an uncompressed protocol field. This discrepancy can lead to a 4-byte misalignment of the network header, potentially causing unaligned access exceptions on certain architectures. To mitigate this vulnerability, the kernel now drops PFC frames for PPPoE sessions and introduces a helper function to streamline the handling of compressed protocol fields.
Users can upgrade to the latest version of the Linux kernel where this vulnerability has been fixed. Instructions for downloading the patched version are available on the official Linux kernel website.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
No SSVC data is available for this CVE.
References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://git.kernel.org/stable/c/0cab5d077dd1efd2bd1a47271acc35894f945b4f | kernel.org | Patch |
| https://git.kernel.org/stable/c/2b5c3c040d020e3ab3b9a8887031202d96843b1e | kernel.org | Patch |
| https://git.kernel.org/stable/c/49e41b60ccd1bdbe9e218420f716dd5f9a2f9c71 | kernel.org | Patch |
| https://git.kernel.org/stable/c/8a5e840babc5c0fbd10c73728a13192347771ec6 | kernel.org | Patch |
| https://git.kernel.org/stable/c/ba758fdf1399f310b30098b6faa3fd043de47dd2 | kernel.org | Patch |
| https://git.kernel.org/stable/c/cb3beef35ab5e0c1afca9fd7648c6ae499786377 | kernel.org | Patch |
| https://git.kernel.org/stable/c/cc1ff87bce1ccd38410ab10960f576dcd17db679 | kernel.org | Patch |
| https://git.kernel.org/stable/c/fcca1df05322bb04e344dd1178b54b76a08eb7c3 | kernel.org | Patch |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| NVD-CWE-noinfo | Insufficient Information to Classify Weakness | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| linux linux kernel | >= 5.0, < 5.10.258 >= 5.11, < 5.15.209 >= 5.16, < 6.1.175 >= 6.2, < 6.6.141 >= 6.7, < 6.12.91 >= 6.13, < 6.18.33 >= 6.19, < 7.0.10 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 14, 2026 | Initial Analysis | [email protected] |
| Jun 28, 2026 | CVE Modified | kernel.org |
| Jun 24, 2026 | New CVE Received | kernel.org |