CVE-2026-98287

Received Received - Intake

BaseFortify

Publication date: 2026-10-06

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: pppoatm: ensure a writable skb header and linear data In pppoatm_send(), LLC encapsulation checks whether there is sufficient headroom for the 4-byte LLC header, but does not ensure that the skb header is writable. Normal transmit packets passing through ppp_start_xmit() have their header unshared via skb_cow_head(). However, packets can also reach pppoatm_send() via PPP channel bridging (PPPIOCBRIDGECHAN) without going through ppp_start_xmit(). Use skb_cow_head() to ensure both sufficient headroom and a writable header before pushing the LLC header. While at it: - Call pskb_may_pull(skb, 1) before inspecting skb->data[0] to prevent out-of-bounds reads on zero-length or non-linear frames (e.g. from bridging). - Defer SC_COMP_PROT protocol compression until after pppoatm_may_send() succeeds. This eliminates the temporary skb allocation on admission failure and completely removes the fragile "undo" heuristic at the nospace label, avoiding any risk of reading uninitialized headroom or performing an unbalanced skb_push().

CVSS Scores

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Meta Information

Published

2026-10-06

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-06

EPSS Evaluated

2026-10-18

NVD

CVE-2026-98287

EUVD

EUVD-2026-93215

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	4cf476ced45d7f12df30a68e833b263e7a2202d1
Linux	Linux	5.11

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves insufficient checks in the pppoatm_send() function. It fails to ensure the skb header is writable before adding a 4-byte LLC header. Packets can bypass normal transmit checks via PPP channel bridging, leading to potential memory corruption or crashes.

Detection Guidance

This vulnerability affects the Linux kernel's pppoatm module and requires kernel-level inspection. Detection involves checking kernel logs for related errors or verifying if the vulnerable code path is present. Use commands like 'dmesg | grep pppoatm' to check for kernel messages. Ensure your kernel version includes the fix by checking 'uname -r' and comparing with patched versions.

Impact Analysis

An attacker could exploit this to cause a kernel crash or execute arbitrary code with kernel privileges. Systems using PPP channel bridging are at higher risk. This may lead to denial-of-service or unauthorized access if exploited.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it pertains to a Linux kernel network packet handling issue in PPPoATM functionality. No evidence suggests it impacts data privacy, security controls, or regulatory requirements.

Mitigation Strategies

Update your Linux kernel to the latest patched version to resolve the pppoatm vulnerability. Ensure your system is running a kernel that includes the fix for CVE-2026-98287.

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