CVE-2026-63912
Received Received - Intake

ESP Out-of-Place Fast Path Length Validation in Linux Kernel

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: restore combined single-frag length gate The ESP out-of-place fast path appends the trailer in esp_output_head() before esp_output_tail() allocates the destination page frag. The head-side gate currently checks skb->data_len and tailen separately, but the tail code allocates a single destination frag from the combined post-trailer skb->data_len. Reject the page-frag fast path when the combined aligned length exceeds a page. Otherwise skb_page_frag_refill() may fall back to a single page while the destination sg still spans the combined skb->data_len. Restore this combined-length page gate for both IPv4 and IPv6.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-63912
EUVD
EUVD-2026-45685

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a flaw in the ESP (Encapsulating Security Payload) out-of-place fast path. The issue occurs when the trailer is appended before allocating the destination page fragment, causing incorrect length checks. The fix restores a gate that rejects the page-frag fast path if the combined aligned length exceeds a page, preventing potential fallbacks to a single page and ensuring proper data handling.

Detection Guidance

This vulnerability is specific to the Linux kernel's ESP (Encapsulating Security Payload) implementation and does not provide direct detection commands. It requires kernel patching or updating to the fixed version. Check your kernel version with uname -r and compare against patched releases.

Impact Analysis

This vulnerability could lead to data corruption or security issues in systems using the Linux kernel's ESP functionality for network encryption. Attackers might exploit it to cause crashes, bypass security measures, or manipulate encrypted traffic if the system relies on the affected fast path for ESP operations.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it pertains to a low-level Linux kernel networking issue involving ESP packet handling. Compliance impacts would only occur if this vulnerability were exploited to compromise data integrity or confidentiality in systems processing sensitive data.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve this vulnerability. Monitor vendor advisories for kernel updates and apply them promptly.

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