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CVE-2026-99072

Linux: ipv4: stop route notification sizing when nexthop group shrinks

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)No scoreNo FIRST EPSS score in this snapshot yet
Fixed in72d9d17092bb37b0717f12042a0817d01a1f9e78Fixed versionCVE List
Published23 Oct 2026Updated 23 Oct 2026CVE List

What fixes it

  • 72d9d17092bb37b0717f12042a0817d01a1f9e78LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

In the Linux kernel, the following vulnerability has been resolved:

ipv4: stop route notification sizing when nexthop group shrinks

Commit 680aea08e78c ("net: ipv4: Emit notification when fib hardware flags are changed") added an RCU-only fib_nlmsg_size() call for asynchronous hardware flag notifications.

fib_nlmsg_size() checks fib_info_num_path() before each iteration, then fib_info_nhc() independently reloads nh->nh_grp. If RTM_NEWNEXTHOP replaces a group with fewer paths between those loads, fib_info_nhc() returns NULL and fib_nexthop_nlmsg_size() dereferences it.

Stop sizing when the indexed path is absent. Nexthop groups are dense, so the current snapshot has no later path.

Text from CVE List

Affected versions 12

  • Linuxaffected: 680aea08e78c003292415518ad270bc20f9c80b1 before 72d9d17092bb37b0717f12042a0817d01a1f9e78CVE List
  • Linuxaffected: 680aea08e78c003292415518ad270bc20f9c80b1 before ad1c9f1b98c92609e9bb2ae8f05916defc3b0a54CVE List
  • Linuxaffected: 680aea08e78c003292415518ad270bc20f9c80b1 before c1f48d1c2d5e9efd904dbbc2f2b3d41543e55c49CVE List
  • Linuxaffected: 680aea08e78c003292415518ad270bc20f9c80b1 before ad2b3a68b8a7d5d27de88e05674e4adb1ce46d88CVE List
  • Linuxaffected: 680aea08e78c003292415518ad270bc20f9c80b1 before d3daa33c7af92e38f2274bbd2576f58bfbaf89e6CVE List
  • Linuxaffected: 5.12CVE List
  • Linuxunaffected: all versions before 5.12CVE List
  • Linuxunaffected: 6.6.160 through 6.6.*CVE List
  • Linuxunaffected: 6.12.113 through 6.12.*CVE List
  • Linuxunaffected: 6.18.57 through 6.18.*CVE List
  • Linuxunaffected: 7.2.11 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5