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CVE-2026-72137— xfrm: nat_keepalive: avoid double free on send error

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.11版本存在安全漏洞，该漏洞源于net/xfrm/xfrm_nat_keepalive.c中nat_keepalive_send()函数在发送错误时释放可能已被网络栈消费的skb，导致双重释放，可能造成系统崩溃或任意代码执行。

CVSS 9.8 · Critical EPSS 0.63% · P47

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae< d0a4dc7efa825bce60a8da8f7d43c864a159abde affected
f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae< 5b0c4c916f202b8fd13d12afb6af62b385622f81 affected
f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae< a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693 affected
f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae< 226f4a490d1a938fc838d8f8c46a4eca864c0d78 affected
6.11 affected
< 6.11 unaffected
6.12.101≤ 6.12.* unaffected
6.18.40≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-72137

Vulnerability Information
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Vulnerability Title
xfrm: nat_keepalive: avoid double free on send error
Source: CVE Program / CVE List V5
Vulnerability 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: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.11版本存在安全漏洞，该漏洞源于net/xfrm/xfrm_nat_keepalive.c中nat_keepalive_send()函数在发送错误时释放可能已被网络栈消费的skb，导致双重释放，可能造成系统崩溃或任意代码执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae ~ d0a4dc7efa825bce60a8da8f7d43c864a159abde -
Linux Linux 6.11 -

II. Public POCs for CVE-2026-72137

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III. Intelligence Information for CVE-2026-72137

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Patches & Fixes for CVE-2026-72137 (4)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-74434 9.8 CRITICAL rxrpc: Don't move a peeked OOB message onto the pending queue
CVE-2026-72065 9.8 CRITICAL net: mana: Validate the packet length reported by the NIC
CVE-2026-72064 9.8 CRITICAL net: mana: Sync page pool RX frags for CPU
CVE-2026-72319 9.8 CRITICAL ipvs: ensure inner headers in ICMP errors are in headroom
CVE-2026-72317 9.8 CRITICAL SUNRPC: pin upper rpc_clnt across the TLS connect_worker
CVE-2026-74427 9.8 CRITICAL afs: Fix netns teardown to cancel the preallocation charger
CVE-2026-72429 9.8 CRITICAL ipv6: ioam: fix type confusion of dst_entry
CVE-2026-74428 9.8 CRITICAL rxrpc: Fix double unlock in rxrpc_recvmsg()
CVE-2026-72139 9.8 CRITICAL tcp: defer md5sig_info kfree past RCU grace period in tcp_connect
CVE-2026-72436 9.8 CRITICAL netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types
CVE-2026-72046 9.8 CRITICAL gve: fix header buffer corruption with header-split and HW-GRO
CVE-2026-72451 9.8 CRITICAL xfrm: Fix xfrm state cache insertion race

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-72137

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