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CVE-2026-74657— ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops

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.

在 Linux 内核中，已修复以下漏洞： ipv4: 修复 fib_nlmsg_size() 对 RTA_VIA 下一跳的处理 fib_nlmsg_size() 仍然假设所有网关都以 IPv4 的 RTA_GATEWAY 属性编码，从而估算下一跳空间大小。然而，IPv4 路由也可能携带 IPv6 网关，而 fib_nexthop_info() 会将其作为 RTA_VIA 转储（dump）。 因此，路由通知（notification）可能分配大小不足的 skb（socket buffer）。随后，fib_dump_i

AI Predicted 5.5 Difficulty: Moderate EPSS 0.17% · P7

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux d15662682db232da77136cd348f4c9df312ca6f9< 0f0ca602941d0a81ae9514943ca06c55159c6385 affected
d15662682db232da77136cd348f4c9df312ca6f9< 5307a53599fa762c06e475ee4a375252074fd324 affected
d15662682db232da77136cd348f4c9df312ca6f9< 7f80ad373ce4a7af5367ff273cea0f16e91387f3 affected
d15662682db232da77136cd348f4c9df312ca6f9< 4a5dfbae5179f6574695012a980476254df2d295 affected
d15662682db232da77136cd348f4c9df312ca6f9< a59edda6eda1252340354322d8ab318b2e9052fb affected
d15662682db232da77136cd348f4c9df312ca6f9< 9b22f13524fa0de0d963bbd3002df6c28bae3395 affected
d15662682db232da77136cd348f4c9df312ca6f9< 4ff9548d84945d2cbf9e4c207288063a200ea397 affected
5.2 affected
… +8 more rows
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I. Basic Information for CVE-2026-74657

Vulnerability Information
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Vulnerability Title
ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops fib_nlmsg_size() still estimates nexthop space as if every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA. As a result, route notifications can allocate an skb that is too small. fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With panic_on_warn set, this becomes a kernel panic. Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is actually present.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux d15662682db232da77136cd348f4c9df312ca6f9 ~ 0f0ca602941d0a81ae9514943ca06c55159c6385 -
Linux Linux 5.2 -

II. Public POCs for CVE-2026-74657

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III. Intelligence Information for CVE-2026-74657

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Patches & Fixes for CVE-2026-74657 (7)

Same Patch Batch · Linux · 2026-08-22 · 150 CVEs total

CVE-2026-74705 10.0 CRITICAL udp: fix potential use-after-free in tunnel segmentation
CVE-2026-74612 10.0 CRITICAL veth: fix skb length accounting after XDP frag adjustment
CVE-2026-74588 9.8 CRITICAL sctp: keep chunk->transport in step with the list it is queued on
CVE-2026-74628 9.8 CRITICAL net/x25: fix use-after-free of the socket by its timers
CVE-2026-74669 9.8 CRITICAL ipvs: clear IPv4 options after rebasing tunnel ICMP errors
CVE-2026-74597 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
CVE-2026-74608 9.8 CRITICAL smb: client: Fix use-after-free in cifs_try_adding_channels()
CVE-2026-74662 9.8 CRITICAL inet: frags: publish queues before arming timer
CVE-2026-74611 9.8 CRITICAL tls: rx: restore msg_iter before TLS 1.3 optimistic retry
CVE-2026-74587 9.8 CRITICAL sctp: fix use-after-free of cached ASCONF chunk
CVE-2026-74688 9.8 CRITICAL sctp: clear control chunk transport if it is being removed
CVE-2026-74723 9.8 CRITICAL btrfs: lzo: reject inline extents without valid headers
CVE-2026-74616 9.8 CRITICAL xdp: reject clones that overrun skb_shared_info tailroom
CVE-2026-74591 9.8 CRITICAL mm/filemap: __filemap_add_folio() restore index before retrying
CVE-2026-74586 9.8 CRITICAL sctp: clear new_transport when removing a peer
CVE-2026-74727 9.8 CRITICAL ovpn: skip rehash for peers already removed from by_id
CVE-2026-74617 9.8 CRITICAL dibs: initialise dibs->lock in dibs_dev_alloc()
CVE-2026-74730 9.8 CRITICAL NFS: Pin the 'struct nfs_server' during a FREE_STATEID call
CVE-2026-74712 9.3 CRITICAL vdpa/mlx5: Fix buffer length in create_direct_keys()
CVE-2026-74665 9.1 CRITICAL net: fix skb length accounting after generic XDP frag adjustment

Showing top 20 of 150 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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