CVE-2026-43037

Published: Mag 01, 2026 Last Modified: Mag 03, 2026

ExploitDB:

Other exploit source:

Google Dorks:

CRITICAL 9,8

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Attack Vector: network

Attack Complexity: low

Privileges Required: none

User Interaction: none

Scope: unchanged

Confidentiality: high

Integrity: high

Availability: high

Description

AI Translation Available

In the Linux kernel, the following vulnerability has been resolved:

ip6_tunnel: clear skb2->cb[] in ip4ip6_err()

Oskar Kjos reported the following problem.

ip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written
by the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes
IPCB(skb2) to __ip_options_echo(), which interprets that cb[] region
as struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff
at offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr
value. __ip_options_echo() then reads optlen from attacker-controlled
packet data at sptr[rr+1] and copies that many bytes into dopt->__data,
a fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE).

To fix this we clear skb2->cb[], as suggested by Oskar Kjos.

Also add minimal IPv4 header validation (version == 4, ihl >= 5).