CVE-2026-53362
Received Received - Intake

Buffer Overflow in Linux Kernel IPv6 Networking

Publication date: 2026-07-04

Last updated on: 2026-07-04

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: account for fraggap on the paged allocation path In __ip6_append_data(), when the paged-allocation branch is taken (MSG_MORE / NETIF_F_SG / large fraglen), alloclen and pagedlen are computed as alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen; datalen already includes fraggap (datalen = length + fraggap). When fraggap is non-zero, this is not the first skb and transhdrlen is zero. The fraggap bytes carried over from the previous skb are copied just past the fragment headers in the new skb's linear area. The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount, and the copy writes past skb->end into the trailing skb_shared_info. An unprivileged user can trigger this via a UDPv6 socket using MSG_MORE together with MSG_SPLICE_PAGES. The bad accounting was introduced by commit 773ba4fe9104 ("ipv6: avoid partial copy for zc"). Before commit ce650a166335 ("udp6: Fix __ip6_append_data()'s handling of MSG_SPLICE_PAGES"), the negative copy value caused -EINVAL to be returned. That later commit allowed MSG_SPLICE_PAGES to proceed in this case, making the corruption triggerable. The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen. After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic. Since a negative copy is no longer expected for a valid MSG_SPLICE_PAGES case, remove the MSG_SPLICE_PAGES exception from the negative copy check.

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Meta Information

Published
2026-07-04
Last Modified
2026-07-04
Generated
2026-07-04
AI Q&A
2026-07-04
EPSS Evaluated
N/A
NVD
CVE-2026-53362
EUVD
EUVD-2026-41669

Affected Vendors & Products

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

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability exists in the Linux kernel's IPv6 implementation, specifically in the __ip6_append_data() function when handling paged allocation with certain flags (MSG_MORE, NETIF_F_SG, large fragment length).

The issue arises because the function incorrectly calculates the lengths for allocation and paging when a 'fraggap' (fragment gap) is present. The data length (datalen) already includes this fraggap, but the function does not properly account for it, leading to an undersized linear area and an overstated paged length.

As a result, copying data writes past the intended buffer boundary into adjacent memory (skb_shared_info), causing memory corruption.

An unprivileged user can trigger this vulnerability by using a UDPv6 socket with the MSG_MORE flag combined with MSG_SPLICE_PAGES, exploiting the bad accounting in the paged allocation path.

Impact Analysis

This vulnerability can lead to memory corruption in the Linux kernel's networking stack.

Since an unprivileged user can trigger it via a UDPv6 socket, it may allow local attackers to cause instability, crashes, or potentially execute arbitrary code with kernel privileges.

Such memory corruption issues can compromise system integrity and security, potentially leading to denial of service or privilege escalation.

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