CVE-2026-43037
Essential information
- Published
- 01/05/2026 15:16
- Modified
- 01/05/2026 15:24
- Author
- —
- Creator
- —
- CISA KEV
- No
- CWE
- —
- CVSS vector
- — — —
Description
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).
NVD status
- Status
- Awaiting Analysis — CVE has been marked for Analysis. Normally once in this state the CVE will be analyzed by NVD staff within 24 hours.
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- NVD
- View on NVD
Affected products (CPE)
| Product | CPE |
|---|---|
| linux / linux kernel | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |