CVE-2026-98570
Received Received - Intake

Buffer Overflow in Linux Kernel IPv6 Networking

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: keep room for the mac header in dst_dev_overhead() The seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as the length they are about to push plus dst_dev_overhead(), then push the new headers and rebuild the mac header below them with skb_mac_header_rebuild(). That rebuild needs skb->mac_len of headroom, but dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device, 16 bytes for plain Ethernet. Where the mac header is longer than that, as it is on ingress through a VLAN device with reorder_hdr off, the rebuild runs out of room: skb_set_mac_header(skb, -skb->mac_len) computes a negative offset, stores it unchecked in the u16 skb->mac_header, and the memmove that follows writes skb->mac_len bytes about 64 KB past skb->head. Forwarding plain ping6 traffic through such a device reproduces it on all five seg6 encapsulation modes and on the rpl and ioam6 inline paths; skb->mac_header comes back as 65534 on a 704-byte head. Return the larger of the two. The helper already returns skb->mac_len when it has no dst, so this only makes the other branch agree, and it covers every caller rather than each call site in turn.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98570
EUVD
EUVD-2026-103615

Affected Vendors & Products

Showing 22 associated CPEs
Vendor Product Version / Range
Linux Linux dce525185bc92864e5a318040285ee070563fe34
Linux Linux dce525185bc92864e5a318040285ee070563fe34
Linux Linux 8471e228448a818e4c27cab4b681b2e758e46cf5
Linux Linux c432cd18a07b623651ed15ea167bd303467004cc
Linux Linux 634710a372ba65bee667c2f6e58a97658c639eab
Linux Linux c447c5a9c47bb4858ab12bf90879fe595d2b7f46
Linux Linux ab9de9c48316d2622d3bf353916b99971570e2c9
Linux Linux 2fcc9f3798ef82399564d247458e69abd10e683b
Linux Linux 371d8dc298b4f59e99b4564ac5d906fce0932c69
Linux Linux b26f015dfb07b6be12d005a0ed0c5c43b7bedbf3
Linux Linux c0b11dc50590e10590b39dcda79835cd32f49d00
Linux Linux 4c12c3c8abd8b888945d31e7bdbb0d8b73032fc5
Linux Linux 25d8e065c7972dc98fd7a4cac322d5367eaede88
Linux Linux 4a855c5aec41bf84922224ab7a74e088776e3ac4
Linux Linux a9f0407414e16176fdbbbd298c9e18d6dfdf96bc
Linux Linux 6.12.16
Linux Linux 6.13.4
Linux Linux 5.15.179
Linux Linux 6.1.130
Linux Linux 6.6.81
Linux Linux 5.10.235
Linux Linux 6.14

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves improper handling of network packet headers during IPv6 forwarding. When processing packets through certain devices like VLAN interfaces, the system fails to reserve enough space for the MAC header. This causes a buffer overflow when rebuilding the header, leading to memory corruption and potential system crashes.

Detection Guidance

This vulnerability affects IPv6 forwarding with specific LWT tunnels (seg6, ioam6, rpl) on Linux systems. Detection requires checking kernel versions and network configurations. Use 'uname -a' to verify kernel version and inspect network interfaces with 'ip link show' for VLAN devices with reorder_hdr off. Monitor for crashes or memory corruption during IPv6 forwarding.

Impact Analysis

This vulnerability could cause denial-of-service conditions by crashing affected systems. It may also allow remote attackers to execute arbitrary code if they can trigger the vulnerable path. Systems using IPv6 with specific network configurations (like VLAN devices with reorder_hdr off) are particularly at risk.

Mitigation Strategies

Apply the latest Linux kernel patches immediately. Disable IPv6 forwarding if not required. Avoid using seg6, ioam6, or rpl LWT tunnels on affected systems. Monitor for unusual crashes or memory corruption in network operations.

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