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CVE-2026-31504— net: fix fanout UAF in packet_release() via NETDEV_UP race

CVSS 7.8 · High EPSS 0.01% · P2
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I. Basic Information for CVE-2026-31504

Vulnerability Information
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Vulnerability Title
net: fix fanout UAF in packet_release() via NETDEV_UP race
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race `packet_release()` has a race window where `NETDEV_UP` can re-register a socket into a fanout group's `arr[]` array. The re-registration is not cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout array. `packet_release()` does NOT zero `po->num` in its `bind_lock` section. After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex` still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)` that already found the socket in `sklist` can re-register the hook. For fanout sockets, this re-registration calls `__fanout_link(sk, po)` which adds the socket back into `f->arr[]` and increments `f->num_members`, but does NOT increment `f->sk_ref`. The fix sets `po->num` to zero in `packet_release` while `bind_lock` is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于NETDEV_UP竞争条件导致fanout释放后重用，可能导致数据包释放时出现悬空指针。
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

VendorProductAffected VersionsCPESubscribe
LinuxLinux ce06b03e60fc19c680d1bf873e779bf11c2fc518 ~ ee642b1962caa9aa231c01abbd58bc453ae6b66e -
LinuxLinux 3.1 -

II. Public POCs for CVE-2026-31504

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III. Intelligence Information for CVE-2026-31504

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Same Patch Batch · Linux · 2026-04-22 · 100 CVEs total

CVE-2026-314789.8 CRITICALksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
CVE-2026-314639.8 CRITICALiomap: fix invalid folio access when i_blkbits differs from I/O granularity
CVE-2026-314449.8 CRITICALksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
CVE-2026-314369.8 CRITICALdmaengine: idxd: fix possible wrong descriptor completion in llist_abort_desc()
CVE-2026-315019.8 CRITICALnet: ti: icssg-prueth: fix use-after-free of CPPI descriptor in RX path
CVE-2026-314489.4 CRITICALext4: avoid infinite loops caused by residual data
CVE-2026-314508.8 HIGHext4: publish jinode after initialization
CVE-2026-314328.8 HIGHksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-314338.8 HIGHksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-314358.8 HIGHnetfs: Fix read abandonment during retry
CVE-2026-314768.2 HIGHksmbd: do not expire session on binding failure
CVE-2026-314648.1 HIGHscsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-315138.1 HIGHBluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-314887.8 HIGHdrm/amd/display: Do not skip unrelated mode changes in DSC validation
CVE-2026-314947.8 HIGHnet: macb: use the current queue number for stats
CVE-2026-314547.8 HIGHxfs: save ailp before dropping the AIL lock in push callbacks
CVE-2026-315027.8 HIGHteam: fix header_ops type confusion with non-Ethernet ports
CVE-2026-314797.8 HIGHdrm/xe: always keep track of remap prev/next
CVE-2026-315057.8 HIGHiavf: fix out-of-bounds writes in iavf_get_ethtool_stats()
CVE-2026-314467.8 HIGHext4: fix use-after-free in update_super_work when racing with umount

Showing top 20 of 100 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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