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CVE-2026-68118— tcp: challenge ACK for non-exact RST in SYN-RECEIVED

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tcp_check_req()在SYN-RECEIVED请求套接字路径中接受窗口内RST而不要求SEG.SEQ与RCV.NXT完全匹配，导致非精确RST会移除请求而非触发挑战ACK。

CVSS 8.2 · High EPSS 0.40% · P33

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 282f23c6ee343126156dd41218b22ece96d747e3< 8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49 affected
282f23c6ee343126156dd41218b22ece96d747e3< 0fe4636665d14a258de70b4f3e8248e6d42038f1 affected
282f23c6ee343126156dd41218b22ece96d747e3< 234f9ffbd9b2c1b24ec67200ea3cff07401bec48 affected
282f23c6ee343126156dd41218b22ece96d747e3< 22cec809b048495310f206d9abbcdbbfbdce3ae3 affected
282f23c6ee343126156dd41218b22ece96d747e3< a28c4fcbf774e23b4779cae468e3497a5ad1f4a1 affected
86791bbfe5ed7b275be040cfeff049a1624af1b7 affected
61f69dc4e40e41b0018f00fa4aeb23d3239556fb affected
34fb350281ced2a72707a5c0064f69992d440edb affected
… +10 more rows
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I. Basic Information for CVE-2026-68118

Vulnerability Information
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Vulnerability Title
tcp: challenge ACK for non-exact RST in SYN-RECEIVED
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: tcp: challenge ACK for non-exact RST in SYN-RECEIVED The SYN-RECEIVED request-socket path in tcp_check_req() accepts an in-window RST without requiring SEG.SEQ to exactly match RCV.NXT. A non-exact RST therefore removes the request instead of eliciting a challenge ACK. RFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in SYN-RECEIVED: an exact RST resets the connection, while a non-exact in-window RST must trigger a challenge ACK and be dropped. Apply that check before the ACK-field validation, following the RFC sequence-number, RST, then ACK processing order. Factor the per-netns challenge ACK quota out of tcp_send_challenge_ack() so request sockets can share it. Use the request socket's send_ack() callback and its own out-of-window ACK timestamp to send and rate-limit the response.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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tcp_check_req()在SYN-RECEIVED请求套接字路径中接受窗口内RST而不要求SEG.SEQ与RCV.NXT完全匹配，导致非精确RST会移除请求而非触发挑战ACK。
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 282f23c6ee343126156dd41218b22ece96d747e3 ~ 8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49 -
Linux Linux 3.6 -

II. Public POCs for CVE-2026-68118

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III. Intelligence Information for CVE-2026-68118

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Patches & Fixes for CVE-2026-68118 (5)

Same Patch Batch · Linux · 2026-08-10 · 344 CVEs total

CVE-2026-68156 9.8 CRITICAL libceph: refresh auth->authorizer_buf{,_len} after authorizer update
CVE-2026-68123 9.8 CRITICAL openvswitch: fix GSO userspace truncation underflow
CVE-2026-68117 9.8 CRITICAL tipc: clear sock->sk on the failed-insert path in tipc_sk_create()
CVE-2026-68127 9.8 CRITICAL ila: reload IPv6 header after pskb_may_pull in checksum adjust
CVE-2026-68300 9.8 CRITICAL sctp: auth: verify auth requirement when auth_chunk is NULL
CVE-2026-68136 9.8 CRITICAL net: gro: fix double aggregation of flush-marked skbs
CVE-2026-68137 9.8 CRITICAL net/x25: fix use-after-free in x25_kill_by_neigh()
CVE-2026-68144 9.8 CRITICAL phonet: pep: fix use-after-free in pep_get_sb()
CVE-2026-68302 9.8 CRITICAL amt: re-read skb header pointers after every pull
CVE-2026-68154 9.8 CRITICAL libceph: reject zero bucket types in crush_decode
CVE-2026-68158 9.8 CRITICAL libceph: Fix multiplication overflow in decode_new_up_state_weight()
CVE-2026-68159 9.8 CRITICAL libceph: bound pg_{temp,upmap,upmap_items} length to CEPH_PG_MAX_SIZE
CVE-2026-68160 9.8 CRITICAL ceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()
CVE-2026-68388 9.8 CRITICAL smb/client: handle overlapping allocated ranges in fallocate
CVE-2026-68170 9.8 CRITICAL mptcp: fix stale skb->sk reference on subflow close
CVE-2026-68385 9.8 CRITICAL s390/checksum: Fix csum_partial() without vector facility
CVE-2026-68426 9.8 CRITICAL xfrm: fix stale skb->prev after async crypto steals a GSO segment
CVE-2026-68381 9.8 CRITICAL ksmbd: pin conn during async oplock break notification
CVE-2026-68161 9.8 CRITICAL sctp: close UDP tunnel sockets during netns teardown
CVE-2026-68124 9.6 CRITICAL mctp: serial: handle zero-length frames to prevent rx buffer overflow

Showing top 20 of 344 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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