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CVE-2026-98438— mptcp: options: fix uninit-value in mptcp_write_data_fin

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： mptcp: options: 修复 mptcp_write_data_fin 中的未初始化值问题 当发送不带数据的 DATA_FIN 时，由于 DATA_FIN 占用连接级序列空间中的 1 个字节 [1]，因此需要添加一个具有特定值的 DSS 映射。 如果已协商校验和，则还需要计算该校验和并将其包含在发出的数据包中，因此初始校验和数据也必须重置为 0。自提交 cfcceb7a39fc（"tcp: 在 __tcp_transmit_skb() 中缩小每包 memset"

AI Predicted 5.5 Difficulty: Hard

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-98438

Vulnerability Information
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Vulnerability Title
mptcp: options: fix uninit-value in mptcp_write_data_fin
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mptcp: options: fix uninit-value in mptcp_write_data_fin When sending a DATA_FIN without data, and because the DATA_FIN occupies 1 octet of the connection-level sequence space [1], it is then required to add a DSS mapping with specific values. If the checksum has been negotiated, it also needs to be computed, and included in the outgoing packet, and thus the initial csum data needs to be reset to 0 as well. This is no longer the case since commit cfcceb7a39fc ("tcp: shrink per-packet memset in __tcp_transmit_skb()"), because the whole ext_copy structure is no longer zeroed by default. This seems to be the only case where use_map is changed and set afterwards, so initialising the csum field only in this case, along with other fields for this specific case.
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux cfcceb7a39fc10a6f896af8229bf81d96acb22cc ~ 9a682067dd7b9dce6b94a0a05661dcc921446402 -
Linux Linux 7.1 -

II. Public POCs for CVE-2026-98438

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III. Intelligence Information for CVE-2026-98438

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Other References for CVE-2026-98438 (2)

Same Patch Batch · Linux · 2026-10-18 · 436 CVEs total

CVE-2026-98583 nfc: nfcmrvl: validate helper command length before pull
CVE-2026-98570 net: ipv6: keep room for the mac header in dst_dev_overhead()
CVE-2026-98571 net: stmmac: clear stale buf->page after recycling on skb build failure
CVE-2026-98572 bpf: Fix immediate JMP JEQ/JNE on MIPS32
CVE-2026-98573 net: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6()
CVE-2026-98574 net: bcmgenet: stop Tx NAPI before disabling the queues
CVE-2026-98575 nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid()
CVE-2026-98576 nfc: llcp: fix slab-out-of-bounds reads when logging service names
CVE-2026-98577 nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap()
CVE-2026-98578 nfc: st21nfca: validate ISO15693 inventory length
CVE-2026-98579 nfc: llcp: fix sdreq TLV list leak on parse/alloc/send failure
CVE-2026-98580 nfc: llcp: Fix race condition in accept_queue lifecycle
CVE-2026-98581 nfc: llcp: Fix list corruption / refcount desync in nfc_llcp_recv_dm()
CVE-2026-98582 nfc: st21nfca: validate received frame size
CVE-2026-98594 tg3: clean up PHYLIB resources on probe failure
CVE-2026-98591 bpf: Fix bounds check for skb-backed dynptrs
CVE-2026-98592 net: spacemit: clear TX descriptor on fragment mapping failure
CVE-2026-98593 s390/debug: Fix NULL pointer dereference in debug_info_copy()
CVE-2026-98590 bpf: Fix bpf_sock context code generation
CVE-2026-98595 udp: remove a disconnected socket from the 4-tuple hash table

Showing top 20 of 436 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98438

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