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CVE-2025-39894— netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于br_nf_local_in函数在确认后检查确认位不当，可能导致内核警告。

CVSS 7.5 · High EPSS 0.33% · P25

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 19

VendorProduct Version RangeStatus
Linux Linux 7c3f28599652acf431a2211168de4a583f30b6d5< d00c8b0daf56012f69075e3377da67878c775e4c affected
2b1414d5e94e477edff1d2c79030f1d742625ea0< ccbad4803225eafe0175d3cb19f0d8d73b504a94 affected
80cd0487f630b5382734997c3e5e3003a77db315< 50db11e2bbb635e38e3dd096215580d6adb41fb0 affected
62e7151ae3eb465e0ab52a20c941ff33bb6332e9< c47ca77fee9071aa543bae592dd2a384f895c8b6 affected
62e7151ae3eb465e0ab52a20c941ff33bb6332e9< a74abcf0f09f59daeecf7a3ba9c1d690808b0afe affected
62e7151ae3eb465e0ab52a20c941ff33bb6332e9< 479a54ab92087318514c82428a87af2d7af1a576 affected
cb734975b0ffa688ff6cc0eed463865bf07b6c01 affected
5.15.151< 5.15.192 affected
… +11 more rows
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I. Basic Information for CVE-2025-39894

Vulnerability Information
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Vulnerability Title
netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm When send a broadcast packet to a tap device, which was added to a bridge, br_nf_local_in() is called to confirm the conntrack. If another conntrack with the same hash value is added to the hash table, which can be triggered by a normal packet to a non-bridge device, the below warning may happen. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 96 at net/bridge/br_netfilter_hooks.c:632 br_nf_local_in+0x168/0x200 CPU: 1 UID: 0 PID: 96 Comm: tap_send Not tainted 6.17.0-rc2-dirty #44 PREEMPT(voluntary) RIP: 0010:br_nf_local_in+0x168/0x200 Call Trace: <TASK> nf_hook_slow+0x3e/0xf0 br_pass_frame_up+0x103/0x180 br_handle_frame_finish+0x2de/0x5b0 br_nf_hook_thresh+0xc0/0x120 br_nf_pre_routing_finish+0x168/0x3a0 br_nf_pre_routing+0x237/0x5e0 br_handle_frame+0x1ec/0x3c0 __netif_receive_skb_core+0x225/0x1210 __netif_receive_skb_one_core+0x37/0xa0 netif_receive_skb+0x36/0x160 tun_get_user+0xa54/0x10c0 tun_chr_write_iter+0x65/0xb0 vfs_write+0x305/0x410 ksys_write+0x60/0xd0 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> ---[ end trace 0000000000000000 ]--- To solve the hash conflict, nf_ct_resolve_clash() try to merge the conntracks, and update skb->_nfct. However, br_nf_local_in() still use the old ct from local variable 'nfct' after confirm(), which leads to this warning. If confirm() does not insert the conntrack entry and return NF_DROP, the warning may also occur. There is no need to reserve the WARN_ON_ONCE, just remove it.
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
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于br_nf_local_in函数在确认后检查确认位不当，可能导致内核警告。
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 7c3f28599652acf431a2211168de4a583f30b6d5 ~ d00c8b0daf56012f69075e3377da67878c775e4c -
Linux Linux 6.8 -

II. Public POCs for CVE-2025-39894

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III. Intelligence Information for CVE-2025-39894

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Patches & Fixes for CVE-2025-39894 (1)

Same Patch Batch · Linux · 2025-10-01 · 169 CVEs total

CVE-2023-53517 9.8 CRITICAL tipc: do not update mtu if msg_max is too small in mtu negotiation
CVE-2023-53454 8.8 HIGH HID: multitouch: Correct devm device reference for hidinput input_dev name
CVE-2025-39918 8.8 HIGH wifi: mt76: fix linked list corruption
CVE-2025-39919 8.8 HIGH wifi: mt76: mt7996: add missing check for rx wcid entries
CVE-2022-50442 8.4 HIGH fs/ntfs3: Validate buffer length while parsing index
CVE-2023-53493 8.4 HIGH accel/qaic: tighten bounds checking in decode_message()
CVE-2022-50421 7.8 HIGH rpmsg: char: Avoid double destroy of default endpoint
CVE-2023-53484 7.8 HIGH lib: cpu_rmap: Avoid use after free on rmap->obj array entries
CVE-2022-50454 7.8 HIGH drm/nouveau: fix a use-after-free in nouveau_gem_prime_import_sg_table()
CVE-2022-50440 7.8 HIGH drm/vmwgfx: Validate the box size for the snooped cursor
CVE-2025-39924 7.8 HIGH erofs: fix invalid algorithm for encoded extents
CVE-2023-53510 7.8 HIGH scsi: ufs: core: Fix handling of lrbp->cmd
CVE-2023-53465 7.8 HIGH soundwire: qcom: fix storing port config out-of-bounds
CVE-2025-39927 7.8 HIGH ceph: fix race condition validating r_parent before applying state
CVE-2023-53506 7.8 HIGH udf: Do not bother merging very long extents
CVE-2022-50437 7.8 HIGH drm/msm/hdmi: fix memory corruption with too many bridges
CVE-2023-53495 7.8 HIGH net: ethernet: mvpp2_main: fix possible OOB write in mvpp2_ethtool_get_rxnfc()
CVE-2023-53494 7.8 HIGH crypto: xts - Handle EBUSY correctly
CVE-2022-50432 7.8 HIGH kernfs: fix use-after-free in __kernfs_remove
CVE-2023-53492 7.8 HIGH netfilter: nf_tables: do not ignore genmask when looking up chain by id

Showing top 20 of 169 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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