AI description
CVE-2026-72137 describes a double-free error found within the Linux kernel's NAT keep-alive implementation. This vulnerability occurs when the `nat_keepalive_send()` function attempts to free a socket buffer (skb) twice. This happens if a send helper reports an error after the packet has already been passed to the output path, where the networking stack might have already consumed and freed the skb. This flaw can lead to undefined memory handling, potentially resulting in memory corruption, a kernel crash, or other unpredictable system behavior. All Linux kernel releases that incorporate the `nat_keepalive_send` path, including both IPv4 and IPv6 stacks, are potentially affected by this issue.
- Description
- In the Linux kernel, the following vulnerability has been resolved: xfrm: nat_keepalive: avoid double free on send error nat_keepalive_send() frees the keepalive skb whenever the IPv4 or IPv6 send helper reports an error. That cleanup is only correct before the skb is handed to the output path. Once ip_build_and_send_pkt() or ip6_xmit() takes ownership, the networking stack may already have consumed the skb before returning an error, so freeing it again is unsafe. Handle the pre-handoff failure cases inside nat_keepalive_send_ipv4() and nat_keepalive_send_ipv6(), where the caller still owns the skb, and keep nat_keepalive_send() responsible only for family dispatch and the unsupported-family cleanup path.
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- NVD status
- Received
CVSS 3.1
- Type
- Secondary
- Base score
- 9.8
- Impact score
- 5.9
- Exploitability score
- 3.9
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Severity
- CRITICAL
Hype score is a measure of social media activity compared against trending CVEs from the past 12 months. Max score 100.
- Hype score
22