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CVE-2026-45840— openvswitch: cap upcall PID array size and pre-size vport replies

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vport netlink回复辅助函数分配固定大小skb但序列化完整upcall PID数组无上限，可能导致CAP_NET_ADMIN用户安装足够大的PID数组溢出回复缓冲区导致nla_put失败触发BUG_ON。

AI Predicted 8.8 Difficulty: Easy EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 5cd667b0a4567048bb555927d6ee564f4e5620a9< 8d59b80e69dddb665eb2de36e62859ab2073470e affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< d9e47e29aacb9f8a9d59feb6ab5b128a9bbb40b0 affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< b39f763d720d623218bc1d95ace6855d7b474e81 affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< f9ef3db77a383d66847fd082c2b437d8ae4d9c63 affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< f99ac36b5d7c719d08a69fcdecce40f78a874e15 affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704 affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< 1d6c02b86329883aa467a3a61f8d34369db73a2f affected
5cd667b0a4567048bb555927d6ee564f4e5620a9< 2091c6aa0df6aba47deb5c8ab232b1cb60af3519 affected
… +10 more rows
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I. Basic Information for CVE-2026-45840

Vulnerability Information
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Vulnerability Title
openvswitch: cap upcall PID array size and pre-size vport replies
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: openvswitch: cap upcall PID array size and pre-size vport replies The vport netlink reply helpers allocate a fixed-size skb with nlmsg_new(NLMSG_DEFAULT_SIZE, ...) but serialize the full upcall PID array via ovs_vport_get_upcall_portids(). Since ovs_vport_set_upcall_portids() accepts any non-zero multiple of sizeof(u32) with no upper bound, a CAP_NET_ADMIN user can install a PID array large enough to overflow the reply buffer, causing nla_put() to fail with -EMSGSIZE and hitting BUG_ON(err < 0). On systems with unprivileged user namespaces enabled (e.g., Ubuntu default), this is reachable via unshare -Urn since OVS vport mutation operations use GENL_UNS_ADMIN_PERM. kernel BUG at net/openvswitch/datapath.c:2414! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 1 UID: 0 PID: 65 Comm: poc Not tainted 7.0.0-rc7-00195-geb216e422044 #1 RIP: 0010:ovs_vport_cmd_set+0x34c/0x400 Call Trace: <TASK> genl_family_rcv_msg_doit (net/netlink/genetlink.c:1116) genl_rcv_msg (net/netlink/genetlink.c:1194) netlink_rcv_skb (net/netlink/af_netlink.c:2550) genl_rcv (net/netlink/genetlink.c:1219) netlink_unicast (net/netlink/af_netlink.c:1344) netlink_sendmsg (net/netlink/af_netlink.c:1894) __sys_sendto (net/socket.c:2206) __x64_sys_sendto (net/socket.c:2209) do_syscall_64 (arch/x86/entry/syscall_64.c:63) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) </TASK> Kernel panic - not syncing: Fatal exception Reject attempts to set more PIDs than nr_cpu_ids in ovs_vport_set_upcall_portids(), and pre-compute the worst-case reply size in ovs_vport_cmd_msg_size() based on that bound, similar to the existing ovs_dp_cmd_msg_size(). nr_cpu_ids matches the cap already used by the per-CPU dispatch configuration on the datapath side (ovs_dp_cmd_fill_info() serialises at most nr_cpu_ids PIDs), so the two sides stay consistent.
Source: CVE Program / CVE List V5
CVSS Information
N/A
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vport netlink回复辅助函数分配固定大小skb但序列化完整upcall PID数组无上限，可能导致CAP_NET_ADMIN用户安装足够大的PID数组溢出回复缓冲区导致nla_put失败触发BUG_ON。
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 5cd667b0a4567048bb555927d6ee564f4e5620a9 ~ 8d59b80e69dddb665eb2de36e62859ab2073470e -
Linux Linux 3.17 -

II. Public POCs for CVE-2026-45840

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-45840

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Patches & Fixes for CVE-2026-45840 (6)

Same Patch Batch · Linux · 2026-05-27 · 275 CVEs total

CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
CVE-2026-46037 8.2 HIGH ipv4: icmp: validate reply type before using icmp_pointers
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2026-46099 8.1 HIGH net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
CVE-2026-46010 8.1 HIGH rxrpc: Fix error handling in rxgk_extract_token()
CVE-2026-46076 7.9 HIGH KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1
CVE-2026-45910 7.8 HIGH RDMA/rxe: Fix race condition in QP timer handlers
CVE-2026-45931 7.8 HIGH accel/amdxdna: Hold mm structure across iommu_sva_unbind_device()
CVE-2026-45956 7.8 HIGH drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
CVE-2026-46036 7.8 HIGH vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex
CVE-2026-46100 7.8 HIGH fs: afs: revert mmap_prepare() change
CVE-2026-45894 7.8 HIGH iommu/vt-d: Clear Present bit before tearing down PASID entry
CVE-2026-45933 7.8 HIGH bpf: Preserve id of register in sync_linked_regs()

Showing top 20 of 275 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-45840

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