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CVE-2026-63978— net/handshake: Drain pending requests at net namespace exit

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基金会开源的一款操作系统内核。 Linux kernel 6.4版本存在安全漏洞，该漏洞源于网络握手模块在退出命名空间时对list_splice_init函数参数传递顺序错误，导致待处理的握手请求未正确清理，攻击者可能利用此漏洞造成资源泄漏或列表损坏。

CVSS 9.8 · Critical EPSS 0.67% · P51

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 3b3009ea8abb713b022d94fba95ec270cf6e7eae< 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd affected
3b3009ea8abb713b022d94fba95ec270cf6e7eae< 2bf24a7e190aae0ea47c78099938ae056c622e44 affected
3b3009ea8abb713b022d94fba95ec270cf6e7eae< 8c35539db0ab0bfa1ea44efab00b053261a69469 affected
3b3009ea8abb713b022d94fba95ec270cf6e7eae< ea5fe6a73ca57e5150b8a38b341aef2636eb72f0 affected
6.4 affected
< 6.4 unaffected
6.12.93≤ 6.12.* unaffected
6.18.44≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-63978

Vulnerability Information
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Vulnerability Title
net/handshake: Drain pending requests at net namespace exit
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/handshake: Drain pending requests at net namespace exit The arguments to list_splice_init() in handshake_net_exit() are reversed. The call moves the local empty "requests" list onto hn->hn_requests, leaving the local list empty, so the subsequent drain loop runs zero iterations. Pending handshake requests that had not yet been accepted are not torn down when the net namespace is destroyed; each one keeps a reference on a socket file and on the handshake_req allocation. Pass the source and destination in the documented order (list_splice_init(list, head) moves list onto head) so the pending list is transferred to the local scratch list and drained through handshake_complete(). Fixing the splice direction exposes a list-corruption race. After the splice each req->hr_list still has non-empty link pointers, threading the stack-local scratch list rather than hn_requests. A concurrent handshake_req_cancel() -- for example, from sunrpc's TLS timeout on a kernel socket whose netns reference was not taken -- finds the request through the rhashtable, calls remove_pending(), and sees !list_empty(&req->hr_list). __remove_pending_locked() then list_del_init()s an entry off the scratch list while the drain iterates, corrupting it. The same call arriving after the drain loop has run list_del() on an entry hits LIST_POISON instead. Have remove_pending() check HANDSHAKE_F_NET_DRAINING under hn_lock and report not-found when drain is in progress. The drain has already taken ownership; handshake_complete()'s existing test_and_set on HANDSHAKE_F_REQ_COMPLETED still arbitrates between drain and cancel for who calls the consumer's hp_done. Use list_del_init() rather than list_del() in the drain so req->hr_list does not carry LIST_POISON after drain releases the entry. The DRAINING guard in remove_pending() makes cancel return false, but cancel still falls through to test_and_set_bit on HANDSHAKE_F_REQ_COMPLETED and drops the request's hr_file reference. Without another pin, if that is the last reference, sk_destruct frees the request while it is still linked on the drain loop's local list. Pin each request's hr_file under hn_lock before releasing the list, and drop that drain pin after the loop finishes with the request.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/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基金会开源的一款操作系统内核。 Linux kernel 6.4版本存在安全漏洞，该漏洞源于网络握手模块在退出命名空间时对list_splice_init函数参数传递顺序错误，导致待处理的握手请求未正确清理，攻击者可能利用此漏洞造成资源泄漏或列表损坏。
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 3b3009ea8abb713b022d94fba95ec270cf6e7eae ~ 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd -
Linux Linux 6.4 -

II. Public POCs for CVE-2026-63978

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III. Intelligence Information for CVE-2026-63978

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Patches & Fixes for CVE-2026-63978 (4)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64136 9.8 CRITICAL smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
CVE-2026-63993 9.8 CRITICAL vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
CVE-2026-53399 9.8 CRITICAL nfsd: release layout stid on setlease failure
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-64089 9.8 CRITICAL batman-adv: tt: fix negative last_changeset_len
CVE-2026-64091 9.8 CRITICAL batman-adv: tt: fix TOCTOU race for reported vlans
CVE-2026-64113 9.8 CRITICAL ixgbevf: fix use-after-free in VEPA multicast source pruning
CVE-2026-64055 9.8 CRITICAL net: ethernet: cortina: Carry over frag counter
CVE-2026-63924 9.8 CRITICAL ipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-64037 9.8 CRITICAL wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled
CVE-2026-63888 9.8 CRITICAL scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-64056 9.8 CRITICAL net: ethernet: cortina: Make RX SKB per-port
CVE-2026-64061 9.8 CRITICAL netfs: Fix early put of sink folio in netfs_read_gaps()
CVE-2026-64125 9.8 CRITICAL net: bcmgenet: keep RBUF EEE/PM disabled
CVE-2026-64102 9.8 CRITICAL RDMA/siw: Reject MPA FPDU length underflow before signed receive math
CVE-2026-63825 9.8 CRITICAL gcov: use atomic counter updates to fix concurrent access crashes

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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