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CVE-2026-81003— net/iucv: filter frames in afiucv_hs_rcv() by ingress device

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afiucv_hs_rcv()未验证帧的入口设备，可能导致帧被传递到不匹配的套接字，造成拒绝服务、数据注入或连接终止。

CVSS 8.1 · High EPSS 0.31% · P22

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 3881ac441f642d56503818123446f7298442236b< 639828ad4d374056167391dbaffd13dd5e5e5ddb affected
3881ac441f642d56503818123446f7298442236b< 92e5c281f1caa287bb58292f2687c9e3ff3aa23e affected
3881ac441f642d56503818123446f7298442236b< 712330f8a4293cfd97b0d62b7c7dc01862a16b98 affected
3881ac441f642d56503818123446f7298442236b< 0a5af67e7184c6a0e155c317840bd64b37177af4 affected
3881ac441f642d56503818123446f7298442236b< dfac2936b83be00035ae176f8252e1c1e1de9207 affected
3881ac441f642d56503818123446f7298442236b< 8e3763f1ccac3fc395f9af2b87114c023ced8a3f affected
3881ac441f642d56503818123446f7298442236b< a7f0130a091724e69827ab58e74777a88747e892 affected
3881ac441f642d56503818123446f7298442236b< 80230a18c164a4b5bbc048fe2768b219ac17bc5a affected
… +10 more rows
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I. Basic Information for CVE-2026-81003

Vulnerability Information
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Vulnerability Title
net/iucv: filter frames in afiucv_hs_rcv() by ingress device
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/iucv: filter frames in afiucv_hs_rcv() by ingress device afiucv_hs_rcv() selects a socket from iucv_sk_list by matching four 8-byte name fields in the transport header alone. No check is made against the net_device the frame arrived on. This can cause a frame arriving on any netdev to be delivered to an AF_IUCV socket. Three problems follow. First, a frame arriving over HiperSockets can be delivered to a socket bound to the classic z/VM IUCV transport, which has iucv->hs_dev == NULL. iucv_sock_bind() takes the classic path whenever the requested userid matches iucv_userid, even on a guest that also has a HiperSockets device carrying the same identifier. The child socket created by afiucv_hs_callback_syn() for such a match inherits hs_dev = NULL and transport = AF_IUCV_TRANS_HIPER, so the first send() on it returns -ENODEV. The socket delivered to accept() is unusable. Second, a frame arriving on one netdev can be delivered to a socket bound to a different IQD device. Which can lead to - Accept-queue exhaustion (DoS) - Attacker-controlled peer identity in the child socket - Data injection into existing sockets - Fabric noise on the IQD fabric, where bogus replies are sent - killing established connections Third, all AF_IUCV sockets live in init_net, as iucv_sock_alloc() calls sk_alloc(&init_net, ...). But even frames arriving on netdev devices in a namespace can be delivered to an IUCV socket. So a process in an unprivileged user and network namespace holding only the CAP_NET_RAW capability valid within that namespace can send a raw ETH_P_AF_IUCV frame on its own lo device and have it matched against init_net sockets. Fix all three by skipping any socket whose hs_dev does not match the ingress device. A classic z/VM IUCV socket has hs_dev == NULL; the ingress dev is never NULL, so classic sockets are skipped automatically. An unbound HIPER socket also has hs_dev == NULL and is skipped. A bound HIPER socket is only reachable from the exact IQD device it was bound to. Because hs_dev is always a device in init_net (iucv_sock_bind() scans for_each_netdev_rcu(&init_net, ...) exclusively), a frame whose ingress device belongs to another namespace never matches any socket. Note that AF_IUCV over HiperSockets provides no per-connection authentication: no sequence numbers, no TLS, no nonce. The four name fields identifying a connection are exchanged in plaintext on the shared HiperSockets segment (VCHID). Any host on the same HiperSockets segment could spoof any frame type against an existing connection. That is a protocol-level property unchanged by this patch. The fix reduces the attack surface to peers present on the same HiperSockets segment.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/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afiucv_hs_rcv()未验证帧的入口设备，可能导致帧被传递到不匹配的套接字，造成拒绝服务、数据注入或连接终止。
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 3881ac441f642d56503818123446f7298442236b ~ 639828ad4d374056167391dbaffd13dd5e5e5ddb -
Linux Linux 3.2 -

II. Public POCs for CVE-2026-81003

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III. Intelligence Information for CVE-2026-81003

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Patches & Fixes for CVE-2026-81003 (7)

Same Patch Batch · Linux · 2026-09-11 · 431 CVEs total

CVE-2026-89688 9.8 CRITICAL nfsd: drop the stateid, not the stateowner, on seqid_op replay retry
CVE-2026-89656 9.8 CRITICAL libceph: reject buckets with mismatched CRUSH ids
CVE-2026-89655 9.8 CRITICAL ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock
CVE-2026-89658 9.8 CRITICAL NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup
CVE-2026-89660 9.8 CRITICAL NFSD: Prevent client use-after-free during admin state revocation
CVE-2026-89659 9.8 CRITICAL NFSD: Prevent client use-after-free during delegation revoke
CVE-2026-89662 9.8 CRITICAL NFSD: Prevent lock owner use-after-free during client teardown
CVE-2026-89669 9.8 CRITICAL nfsd: initialize copy-notify stateid before publishing it
CVE-2026-89674 9.8 CRITICAL nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget
CVE-2026-89675 9.8 CRITICAL nfsd: fix UAF in async copy cancel and shutdown
CVE-2026-89676 9.8 CRITICAL nfsd: fix stale s2s_cp_stateids IDR entry for async COPY
CVE-2026-89677 9.8 CRITICAL nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file()
CVE-2026-89681 9.8 CRITICAL nfsd: fix layout fence worker double-reference race
CVE-2026-89686 9.8 CRITICAL nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke
CVE-2026-89478 9.8 CRITICAL sctp: drop a chunk if its transport was removed
CVE-2026-89479 9.8 CRITICAL sctp: stop processing a packet once its association is deleted
CVE-2026-89702 9.8 CRITICAL nfsd: size fh_verify server sockaddr slot by xpt_locallen
CVE-2026-89703 9.8 CRITICAL nfsd: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations
CVE-2026-89482 9.8 CRITICAL nvme-tcp: do not accept C2HData based on blk_rq_payload_bytes() alone
CVE-2026-89708 9.8 CRITICAL nfsd: RCU-protect cl_cb_session to fix use-after-free on session teardown

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-81003

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