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CVE-2026-72421— ipv4: fib: Don't ignore error route in local/main tables.

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fib_lookup()执行路由查找时未正确退出，导致错误路由被默认表中的其他路由覆盖，可能引起路由选择不一致，造成非预期网络访问。

CVSS 10.0 · Critical EPSS 0.56% · P44

Possible ATT&CK Techniques 1 AI

T1044

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux f4530fa574df4d833506c53697ed1daa0d390bf4< a29e95fbc51e8a1b932773fd0e259b2080881443 affected
f4530fa574df4d833506c53697ed1daa0d390bf4< 5ae18d87a45698e8244d0fcba64c658c35a7dd3d affected
f4530fa574df4d833506c53697ed1daa0d390bf4< 9127589aabdee588278e8d0d0bd3709a760a92c8 affected
f4530fa574df4d833506c53697ed1daa0d390bf4< 49eaf1403201357762d745a35882fb734107d763 affected
f4530fa574df4d833506c53697ed1daa0d390bf4< fd25996f57a95d56bc568c89b4921edcf334b7d8 affected
f4530fa574df4d833506c53697ed1daa0d390bf4< 828fad4fd418bcdb9f5d66fec0d184c52a85ec31 affected
f4530fa574df4d833506c53697ed1daa0d390bf4< a668fa160247d7bbe921548cb845f607b8b9305f affected
f4530fa574df4d833506c53697ed1daa0d390bf4< b72f0db64205d9ce462038ba995d5d31eff32dc1 affected
… +10 more rows
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I. Basic Information for CVE-2026-72421

Vulnerability Information
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Vulnerability Title
ipv4: fib: Don't ignore error route in local/main tables.
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: Don't ignore error route in local/main tables. When CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added, fib_lookup() performs route lookup directly on two tables. Since the first lookup does not properly bail out, the result of an error route in the merged local/main table could be overwritten by another route in the default table: # unshare -n # ip link set lo up # ip route add 192.168.0.0/24 dev lo table 253 # ip route add unreachable 192.168.0.0/24 # ip route get 192.168.0.1 192.168.0.1 dev lo table default uid 0 cache <local> Once a random rule is added, the error route is respected: # ip rule add table 0 # ip rule del table 0 # ip route get 192.168.0.1 RTNETLINK answers: No route to host Let's fix the inconsistent behaviour.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
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fib_lookup()执行路由查找时未正确退出，导致错误路由被默认表中的其他路由覆盖，可能引起路由选择不一致，造成非预期网络访问。
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 f4530fa574df4d833506c53697ed1daa0d390bf4 ~ a29e95fbc51e8a1b932773fd0e259b2080881443 -
Linux Linux 3.6 -

II. Public POCs for CVE-2026-72421

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III. Intelligence Information for CVE-2026-72421

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Patches & Fixes for CVE-2026-72421 (7)

Other References for CVE-2026-72421 (1)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-74436 9.8 CRITICAL rxrpc: serialize kernel accept preallocation with socket teardown
CVE-2026-74428 9.8 CRITICAL rxrpc: Fix double unlock in rxrpc_recvmsg()
CVE-2026-72472 9.8 CRITICAL nfs: use nfsi->rwsem to protect traversal of the file lock list
CVE-2026-72473 9.8 CRITICAL xprtrdma: Decouple req recycling from RPC completion
CVE-2026-74433 9.8 CRITICAL rxrpc: Fix UAF in rxgk_issue_challenge()
CVE-2026-72098 9.8 CRITICAL dm-verity: fix buffer overflow in FEC calculation
CVE-2026-74434 9.8 CRITICAL rxrpc: Don't move a peeked OOB message onto the pending queue
CVE-2026-72299 9.8 CRITICAL tipc: restrict socket queue dumps in enqueue tracepoints
CVE-2026-72130 9.8 CRITICAL nvmet-auth: reject short AUTH_RECEIVE buffers
CVE-2026-72248 9.8 CRITICAL netfilter: flowtable: support IPIP tunnel with direct xmit
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-72251 9.8 CRITICAL netfilter: nf_nat_sip: reload possible stale data pointer
CVE-2026-72491 9.8 CRITICAL net/9p: fix race condition on rdma->state in trans_rdma.c

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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