CVE-2026-89968— nvmet-tcp: reject unsolicited H2CData PDUs
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.
在 Linux 内核中，以下漏洞已得到修复： nvmet-tcp：拒绝未经请求的 H2CData PDU 函数在接收到 H2CData PDU 时，仅检查其 TTAG 是否为有效的、处于有效范围内的命令索引，以及该命令的数据缓冲区是否已映射。但它从未检查目标端是否实际上已通过为该命令发送 R2T（Ready to Transfer）来请求这些数据。 远程主机可利用此漏洞。具体场景如下：主机提交一个走 R2T 路径的写命令，并在目标端发送 R2T 之前，提前发送针对该命令标签的 H2CData PDU。这会导致该命令
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing ApplicationAffected Version Matrix 18
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 872d26a391da92ed8f0c0f5cb5fef428067b7f30< 02341ee424fb2eed16b5b8a9d247492e49335c21 |
affected |
872d26a391da92ed8f0c0f5cb5fef428067b7f30< cade124c06f8e738e3a0df285ed2e08953e6bfaa |
affected | ||
872d26a391da92ed8f0c0f5cb5fef428067b7f30< 14beef7d4f123fb458fc9844aa74a071871dcca6 |
affected | ||
872d26a391da92ed8f0c0f5cb5fef428067b7f30< 9fb527103e53fd43a8e802c2eca407869c204f7a |
affected | ||
872d26a391da92ed8f0c0f5cb5fef428067b7f30< 2b71f9193e3d3a352920ba367f1a6db345249038 |
affected | ||
872d26a391da92ed8f0c0f5cb5fef428067b7f30< cf1484d9a75de6809ef331e16f525aaa41b0e16d |
affected | ||
872d26a391da92ed8f0c0f5cb5fef428067b7f30< 1cbed7538946c99e585acefd11c9ba3a0bdbae05 |
affected | ||
872d26a391da92ed8f0c0f5cb5fef428067b7f30< db62b35cbca052860c519cbcabe7650708528738 |
affected | ||
| … +10 more rows | |||
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I. Basic Information for CVE-2026-89968
Vulnerability Information
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Vulnerability Title
nvmet-tcp: reject unsolicited H2CData PDUs
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
nvmet-tcp: reject unsolicited H2CData PDUs
nvmet_tcp_handle_h2c_data_pdu() accepts an H2CData PDU after only checking
that its TTAG is a valid in-range command index and that the command's
data buffers are mapped. It never checks that the target has actually
solicited that data by sending an R2T for the command.
A remote host can abuse this. It submits a write command that takes the
R2T path and, before the target transmits the R2T, sends an H2CData PDU
for that command's tag. The data completes the command early, and when
the command then fails synchronously (e.g. a length mismatch caught by
nvmet_check_transfer_len()), it is completed a second time. Each
completion calls nvmet_tcp_queue_response(), so the same command is added
to queue->resp_list twice while it is still linked; the second llist_add()
makes the node point to itself (lentry->next == lentry).
nvmet_tcp_process_resp_list() then walks that self-referential node and
adds the command to resp_send_list twice. With CONFIG_DEBUG_LIST this
trips the "list_add double add" check (kernel BUG); without it the loop
never terminates and the nvmet_tcp workqueue wedges (soft-lockup). It is
remotely triggerable and needs no authentication on an allow_any_host
subsystem.
Track whether an R2T has been transmitted for a command and reject an
H2CData PDU that arrives before it. The flag is cleared on command reuse
(nvmet_tcp_get_cmd() zeroes cmd->flags) and stays set across the multiple
H2CData PDUs of a single solicited transfer.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-89968
| # | POC Description | Source Link | Shenlong Link |
|---|
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Other References for CVE-2026-89968 (8)
Same Patch Batch · Linux · 2026-09-16 · 276 CVEs total
| CVE-2026-90048 | 9.8 CRITICAL | fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list() |
| CVE-2026-90012 | 9.8 CRITICAL | spi: Fix DMA mapping ownership on partial map failure |
| CVE-2026-89970 | 9.8 CRITICAL | nvmet-auth: Synchronize timeout work during SQ teardown |
| CVE-2026-89857 | 9.8 CRITICAL | scsi: qla2xxx: Hold qpair lock when sending NVMe LS reject |
| CVE-2026-89969 | 9.8 CRITICAL | nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU |
| CVE-2026-89847 | 9.8 CRITICAL | scsi: qla2xxx: Avoid double completion in async IOCB timeout |
| CVE-2026-89972 | 9.8 CRITICAL | nvme: add missing SRCU grace period in error path |
| CVE-2026-89990 | 9.8 CRITICAL | ceph: lock mutex in ceph_mds_check_access() |
| CVE-2026-90036 | 9.8 CRITICAL | NFSD: Prevent client use-after-free during blocked-lock reaping |
| CVE-2026-90038 | 9.8 CRITICAL | NFSD: Prevent client use-after-free during export state revocation |
| CVE-2026-90037 | 9.8 CRITICAL | NFSD: Prevent client use-after-free during close_lru reaping |
| CVE-2026-89788 | 9.8 CRITICAL | ksmbd: fix tree connection use-after-free in smb2_tree_connect() |
| CVE-2026-89783 | 9.8 CRITICAL | xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full |
| CVE-2026-90042 | 9.8 CRITICAL | ceph: properly decrypt filenames in vmalloc() buffers |
| CVE-2026-89778 | 9.8 CRITICAL | isofs: fix out-of-bounds page array access on empty zisofs block |
| CVE-2026-89915 | 9.3 CRITICAL | KVM: arm64: Remove VM-wide VNCR mapping counter |
| CVE-2026-90049 | 9.3 CRITICAL | net: skbuff: don't skb_tx_error() the source skb in skb_zerocopy() |
| CVE-2026-89775 | 9.3 CRITICAL | KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation |
| CVE-2026-89916 | 9.3 CRITICAL | KVM: arm64: Make VNCR invalidation participate in MMU invalidation retry |
| CVE-2026-89930 | 9.3 CRITICAL | KVM: nVMX: Service local TLB flushes on failed nested VM-Enter |
Showing top 20 of 276 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
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Same vendor: Linux
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CVE-2026-98385
sched/cache: Decouple sched_cache_group from mm to fix UAF -
CVE-2026-98384
bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destr -
CVE-2026-98383
bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL -
CVE-2026-98382
bpf: Reject dev-bound-only programs on other devices -
CVE-2026-98381
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