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CVE-2025-40123— bpf: Enforce expected_attach_type for tailcall compatibility

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attach类型验证不足，可能导致空指针取消引用。

CVSS 7.8 · High EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 5e43f899b03a3492ce5fc44e8900becb04dae9c0< e53a59e7cee5c1605d1ed595933098c2b69108f9 affected
5e43f899b03a3492ce5fc44e8900becb04dae9c0< dc4f348952173beb8ceb15be30b249276eccb605 affected
5e43f899b03a3492ce5fc44e8900becb04dae9c0< a99de19128aec0913f3d529f529fbbff5edfaff8 affected
5e43f899b03a3492ce5fc44e8900becb04dae9c0< 08cb3dc9d2b44f153d0bcf2cb966e4a94b5d0f32 affected
5e43f899b03a3492ce5fc44e8900becb04dae9c0< f856c598080ba7ce1252867b8ecd6ad5bdaf9a6a affected
5e43f899b03a3492ce5fc44e8900becb04dae9c0< c1ad19b5d8e23123503dcaf2d4342e1b90b923ad affected
5e43f899b03a3492ce5fc44e8900becb04dae9c0< 4540aed51b12bc13364149bf95f6ecef013197c0 affected
4.17 affected
… +8 more rows
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I. Basic Information for CVE-2025-40123

Vulnerability Information
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Vulnerability Title
bpf: Enforce expected_attach_type for tailcall compatibility
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Enforce expected_attach_type for tailcall compatibility Yinhao et al. recently reported: Our fuzzer tool discovered an uninitialized pointer issue in the bpf_prog_test_run_xdp() function within the Linux kernel's BPF subsystem. This leads to a NULL pointer dereference when a BPF program attempts to deference the txq member of struct xdp_buff object. The test initializes two programs of BPF_PROG_TYPE_XDP: progA acts as the entry point for bpf_prog_test_run_xdp() and its expected_attach_type can neither be of be BPF_XDP_DEVMAP nor BPF_XDP_CPUMAP. progA calls into a slot of a tailcall map it owns. progB's expected_attach_type must be BPF_XDP_DEVMAP to pass xdp_is_valid_access() validation. The program returns struct xdp_md's egress_ifindex, and the latter is only allowed to be accessed under mentioned expected_attach_type. progB is then inserted into the tailcall which progA calls. The underlying issue goes beyond XDP though. Another example are programs of type BPF_PROG_TYPE_CGROUP_SOCK_ADDR. sock_addr_is_valid_access() as well as sock_addr_func_proto() have different logic depending on the programs' expected_attach_type. Similarly, a program attached to BPF_CGROUP_INET4_GETPEERNAME should not be allowed doing a tailcall into a program which calls bpf_bind() out of BPF which is only enabled for BPF_CGROUP_INET4_CONNECT. In short, specifying expected_attach_type allows to open up additional functionality or restrictions beyond what the basic bpf_prog_type enables. The use of tailcalls must not violate these constraints. Fix it by enforcing expected_attach_type in __bpf_prog_map_compatible(). Note that we only enforce this for tailcall maps, but not for BPF devmaps or cpumaps: There, the programs are invoked through dev_map_bpf_prog_run*() and cpu_map_bpf_prog_run*() which set up a new environment / context and therefore these situations are not prone to this issue.
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attach类型验证不足，可能导致空指针取消引用。
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 5e43f899b03a3492ce5fc44e8900becb04dae9c0 ~ e53a59e7cee5c1605d1ed595933098c2b69108f9 -
Linux Linux 4.17 -

II. Public POCs for CVE-2025-40123

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III. Intelligence Information for CVE-2025-40123

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Patches & Fixes for CVE-2025-40123 (2)

Same Patch Batch · Linux · 2025-11-12 · 96 CVEs total

CVE-2025-40176 9.8 CRITICAL tls: wait for pending async decryptions if tls_strp_msg_hold fails
CVE-2025-40140 8.8 HIGH net: usb: Remove disruptive netif_wake_queue in rtl8150_set_multicast
CVE-2025-40135 8.1 HIGH ipv6: use RCU in ip6_xmit()
CVE-2025-40158 8.1 HIGH ipv6: use RCU in ip6_output()
CVE-2025-40186 8.1 HIGH tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().
CVE-2025-40204 8.1 HIGH sctp: Fix MAC comparison to be constant-time
CVE-2025-40133 8.1 HIGH mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().
CVE-2025-40168 8.1 HIGH smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match().
CVE-2025-40141 8.0 HIGH Bluetooth: ISO: Fix possible UAF on iso_conn_free
CVE-2025-40149 7.8 HIGH tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for_sock().
CVE-2025-40190 7.8 HIGH ext4: guard against EA inode refcount underflow in xattr update
CVE-2025-40139 7.8 HIGH smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().
CVE-2025-40151 7.8 HIGH LoongArch: BPF: No support of struct argument in trampoline programs
CVE-2025-40159 7.8 HIGH xsk: Harden userspace-supplied xdp_desc validation
CVE-2025-40165 7.8 HIGH media: nxp: imx8-isi: m2m: Fix streaming cleanup on release
CVE-2025-40174 7.8 HIGH x86/mm: Fix SMP ordering in switch_mm_irqs_off()
CVE-2025-40172 7.8 HIGH accel/qaic: Treat remaining == 0 as error in find_and_map_user_pages()
CVE-2025-40170 7.8 HIGH net: use dst_dev_rcu() in sk_setup_caps()
CVE-2025-40169 7.8 HIGH bpf: Reject negative offsets for ALU ops
CVE-2025-40167 7.8 HIGH ext4: detect invalid INLINE_DATA + EXTENTS flag combination

Showing top 20 of 96 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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