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CVE-2026-31685— netfilter: ip6t_eui64: reject invalid MAC header for all packets

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ip6t_eui64中MAC标头有效性检查条件错误，可能导致访问无效MAC标头。

CVSS 9.4 · Critical EPSS 0.39% · P31

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 4d75bc2cd093bf5803edf512c099bfb220fd6459 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 7d6a57411caf54df025860c9b1a82cd42d57a562 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< d5603591373441fecf9951833d6d873e09320f08 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 288138418bef956f8b295751a4536c60f0e89f4a affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 9eda5478746ef7dc0e4e537b5a5e4b0ca1027091 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 807d6ee15804df6f01a35c910f09612e858739a6 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 309ae3e9a51a69699ca94eac5fac5688fa562d55 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< fdce0b3590f724540795b874b4c8850c90e6b0a8 affected
… +10 more rows
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I. Basic Information for CVE-2026-31685

Vulnerability Information
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Vulnerability Title
netfilter: ip6t_eui64: reject invalid MAC header for all packets
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_eui64: reject invalid MAC header for all packets `eui64_mt6()` derives a modified EUI-64 from the Ethernet source address and compares it with the low 64 bits of the IPv6 source address. The existing guard only rejects an invalid MAC header when `par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()` can still reach `eth_hdr(skb)` even when the MAC header is not valid. Fix this by removing the `par->fragoff != 0` condition so that packets with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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ip6t_eui64中MAC标头有效性检查条件错误，可能导致访问无效MAC标头。
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)

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Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ 4d75bc2cd093bf5803edf512c099bfb220fd6459 -
Linux Linux 2.6.12 -

II. Public POCs for CVE-2026-31685

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III. Intelligence Information for CVE-2026-31685

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Patches & Fixes for CVE-2026-31685 (3)

Same Patch Batch · Linux · 2026-04-25 · 13 CVEs total

CVE-2026-31682 9.1 CRITICAL bridge: br_nd_send: linearize skb before parsing ND options
CVE-2026-31683 7.8 HIGH batman-adv: avoid OGM aggregation when skb tailroom is insufficient
CVE-2026-31680 7.8 HIGH net: ipv6: flowlabel: defer exclusive option free until RCU teardown
CVE-2026-31678 7.8 HIGH openvswitch: defer tunnel netdev_put to RCU release
CVE-2026-31675 7.8 HIGH net/sched: sch_netem: fix out-of-bounds access in packet corruption
CVE-2026-31673 7.8 HIGH af_unix: read UNIX_DIAG_VFS data under unix_state_lock
CVE-2026-31676 7.5 HIGH rxrpc: only handle RESPONSE during service challenge
CVE-2026-31679 7.1 HIGH openvswitch: validate MPLS set/set_masked payload length
CVE-2026-31674 7.1 HIGH netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check()
CVE-2026-31684 net: sched: act_csum: validate nested VLAN headers
CVE-2026-31681 netfilter: xt_multiport: validate range encoding in checkentry
CVE-2026-31677 crypto: af_alg - limit RX SG extraction by receive buffer budget

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31685

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