CVE-2024-26665: tunnels: fix out of bounds access when building IPv6 PMTU error

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-04-02 · updated 2026-08-04
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: tunnels: fix out of bounds access when building IPv6 PMTU error If the ICMPv6 error is built from a non-linear skb we get the following splat, BUG: KASAN: slab-out-of-bounds in do_csum+0x220/0x240 Read of size 4 at addr ffff88811d402c80 by task netperf/820 CPU: 0 PID: 820 Comm: netperf Not tainted 6.8.0-rc1+ #543 ... kasan_report+0xd8/0x110 do_csum+0x220/0x240 csum_partial+0xc/0x20 skb_tunnel_check_pmtu+0xeb9/0x3280 vxlan_xmit_one+0x14c2/0x4080 vxlan_xmit+0xf61/0x5c00 dev_hard_start_xmit+0xfb/0x510 __dev_queue_xmit+0x7cd/0x32a0 br_dev_queue_push_xmit+0x39d/0x6a0 Use skb_checksum instead of csum_partial who cannot deal with non-linear SKBs.

Affected products

Debian Linux: 10.0
Linux kernel: from 5.9 before 5.10.210; from 5.11 before 5.15.149; from 5.16 before 6.1.78; from 6.2 before 6.6.17; from 6.7 before 6.7.5; 6.8-rc1, 6.8-rc2, 6.8-rc3 — fixed in 5.10.210, 5.15.149, 6.1.78, 6.6.17, 6.7.5

How to fix

Upgrade to a fixed version: Linux kernel 5.10.210, 5.15.149, 6.1.78, 6.6.17. Check the vendor advisory for mitigations.

References

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