CVE-2026-63994

CriticalCVSS 9.8/10Last modified Oct 19, 2026

Description

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

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()

Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head.

Fix this possible UAF by initializing the local variables after the skb_cow() call.

Remove skb_reset_network_header() calls which were not needed.

Metrics

CVSS 3.1 9.8/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-416

Affected software

No affected versions have been published.

Timeline

Published
Jul 19, 2026
Last modified
Oct 19, 2026
NVD status
Modified

Related CVEs from 2026

CVE-2026-639957.8In the Linux kernel, the following vulnerability has been resolved: ethtool: cmis: validate start_cmd_payload_size from module The CMIS fiCVE-2026-639967.8In the Linux kernel, the following vulnerability has been resolved: ethtool: cmis: require exact CDB reply length Malicious SFP module couCVE-2026-639975.5In the Linux kernel, the following vulnerability has been resolved: ethtool: module: avoid leaking a netdev ref on module flash errors modCVE-2026-639985.5In the Linux kernel, the following vulnerability has been resolved: ethtool: module: call ethnl_ops_complete() on module flash errors WhenCVE-2026-639995.5In the Linux kernel, the following vulnerability has been resolved: ethtool: rss: fix indir_table and hkey leak on get_rxfh failure rss_prCVE-2026-64004.3The Child Height Predictor by Ostheimer plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to and includingCVE-2026-640009.8In the Linux kernel, the following vulnerability has been resolved: net: hsr: fix potential OOB access in supervision frame handling EnsurCVE-2026-640017.8In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: oss: Fix setup list UAF on proc write error snd_pcm_oss_proCVE-2026-640027.8In the Linux kernel, the following vulnerability has been resolved: ipv4: free net->ipv4.sysctl_local_reserved_ports after unregister_net_sCVE-2026-640037.5In the Linux kernel, the following vulnerability has been resolved: scsi: core: Run queues for all non-SDEV_DEL devices from scsi_run_host_CVE-2026-640047.8In the Linux kernel, the following vulnerability has been resolved: net/iucv: fix locking in .getsockopt Mirror iucv_sock_setsockopt() andCVE-2026-640057.8In the Linux kernel, the following vulnerability has been resolved: net/smc: Do not re-initialize smc hashtables INIT_HLIST_HEAD(&smc_v*_h
CVE-2026-63994: Critical severity, CVSS 9.8 | Vulnix