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CVE-2026-74496— fou: Fix use-after-free in fou_create()

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存在安全漏洞，该漏洞源于fou_create()在将新FOU端口添加至per-netns列表前通过sk_user_data发布struct fou，若fou_add_to_port_list()失败，错误路径释放fou但sk_user_data仍可访问，可能导致释放后重用。

CVSS 7.8 · High EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 23461551c00628c3f3fe9cf837bf53cf8f212b63< a28d8903bfe76089ea4bbdbff9976965f9ef8107 affected
23461551c00628c3f3fe9cf837bf53cf8f212b63< b14361aca6350ff7907b0e9903c7b94dc7d5d4a0 affected
3.18 affected
< 3.18 unaffected
7.1.8≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-74496

Vulnerability Information
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Vulnerability Title
fou: Fix use-after-free in fou_create()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/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存在安全漏洞，该漏洞源于fou_create()在将新FOU端口添加至per-netns列表前通过sk_user_data发布struct fou，若fou_add_to_port_list()失败，错误路径释放fou但sk_user_data仍可访问，可能导致释放后重用。
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 23461551c00628c3f3fe9cf837bf53cf8f212b63 ~ a28d8903bfe76089ea4bbdbff9976965f9ef8107 -
Linux Linux 3.18 -

II. Public POCs for CVE-2026-74496

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III. Intelligence Information for CVE-2026-74496

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Patches & Fixes for CVE-2026-74496 (2)

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

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
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-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72041 9.8 CRITICAL espintcp: use sk_msg_free_partial to fix partial send
CVE-2026-72477 9.8 CRITICAL fs/ntfs3: call _ntfs_bad_inode() when failing to rename
CVE-2026-72209 9.8 CRITICAL ntfs: validate attribute values on lookup
CVE-2026-72208 9.8 CRITICAL ntfs: add bounds check before accessing EA entries
CVE-2026-72206 9.8 CRITICAL ntfs: validate index block header more strictly
CVE-2026-72299 9.8 CRITICAL tipc: restrict socket queue dumps in enqueue tracepoints
CVE-2026-74434 9.8 CRITICAL rxrpc: Don't move a peeked OOB message onto the pending queue
CVE-2026-74433 9.8 CRITICAL rxrpc: Fix UAF in rxgk_issue_challenge()
CVE-2026-72473 9.8 CRITICAL xprtrdma: Decouple req recycling from RPC completion
CVE-2026-72472 9.8 CRITICAL nfs: use nfsi->rwsem to protect traversal of the file lock list
CVE-2026-74545 9.8 CRITICAL rtase: fix double free of multi-frag skb on DMA map failure
CVE-2026-72322 9.8 CRITICAL ipv6: mcast: Fix potential UAF in MLD delayed work

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-2026-74496

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