CVE-2026-89562

ip6_gre: fix hardware header length for NBMA tunnels

HIGH

7.8

CVSS Score

Published: September 11, 2026 at 07:44 PM UTC

Updated: October 19, 2026 at 09:17 AM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

HIGH7.8

Exploit prediction

EPSS 0.1%

Description

In the Linux kernel, the following vulnerability has been resolved: ip6_gre: fix hardware header length for NBMA tunnels ip6gre_tnl_link_config_route() accumulates the lower device's hardware header length into dev->hard_header_len whenever header_ops is set. This is incorrect for both users of header_ops. ip6gretap and ip6erspan have a fixed Ethernet hardware header length. For an NBMA ip6gre tunnel, ip6gre_header() creates only the GRE header, the optional FOU or GUE header, and the outer IPv6 header. The lower device header is headroom needed later, not part of the tunnel device's hardware header. Keep the lower device header in needed_headroom. Set hard_header_len to the tunnel header length only for ARPHRD_IP6GRE devices with header_ops, and leave the fixed Ethernet header length unchanged for tap and erspan devices.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

90%

187a6daf5db45adc807c85bbe285319107bed1984.19.162 5.10 5.4.82 5.9.13832ba596494b2c9eac7760259eff2d8b7dcad0eecf3d9717a5271573fa193c4dfa0df856295d5b15d9897bb66ce989325b4bf4cdbb6a799e4ac878b6

Vendor states this is fixed in 505b6d296c486ef7d1274f279d4c43a172f63224 (fixed)

Vendor states this is fixed in 565038b0092f65afe384961c0f548d605bf438b9 (fixed)

Vendor states this is fixed in 7719f6e7ed2ffddc2c3bb61f4467b76d49e0af6a (fixed)

Vendor states this is fixed in 8bfe746afee38dd6e4348ddcd22d554789dbb9ff (fixed)

Vendor states this is fixed in b1e95e3602d8e112458627f14c6c31c21f2188cb (fixed)

Vendor states this is fixed in b8282668d8fa7c61b80e8e4890729031c291a16c (fixed)

Vendor states this is fixed in c3457a5aae5fb43f7023d3f3dc472c2afa22acf0 (fixed)

Vendor states this is fixed in cb1afd087aedc90e5274537e4fb9bf3f98e5afdb (fixed)

Affected range stops below 4.20, so it looks safe — our inference, not a vendor statement

Vendor states this is fixed in 5.10 (unaffected)

Vendor states this is fixed in 5.10.270 (unaffected)

Vendor states this is fixed in 5.15.221 (unaffected)