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Vulnerabilities

Vulnerability · CVE-2026-99201

CVE-2026-99201: netlink: avoid hashing the network namespace pointer

Published Oct 28, 2026 · catalog updated Oct 28, 2026 · Linux Linux

Last checked Oct 31, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-99201. EPSS is 0.17%. Act only if a listed version of Linux Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Low—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.17%
Remediation
Advisory link
Affected products
Debian:12 linux · Debian:13 linux · Debian:14 linux · linux kernel · vendor Linux Linux

In the Linux kernel, the following vulnerability has been resolved: netlink: avoid hashing the network namespace pointer The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/netlink and socket diagnostics expose the table's bucket order. By binding and rebinding chosen NETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal buckets and recover the low bits of the Jenkins hash. Its 32-bit seed and the limited set of kernel-image slides can then be searched offline to recover the address of init_net. Use the namespace's unique, non-address net_cookie in the comparison key instead. It is assigned before the per-net initializers run and remains unchanged for the namespace's lifetime. The lookup key and object hash are still built by netlink_compare_arg_init(), keeping lookup, insertion, removal and rehashing consistent while preserving namespace separation. Neither public table walker needs to change. Reading the socket's namespace cookie in netlink_compare() is safe under RCU, including during namespace teardown. netlink_release() removes the socket from the hash table and defers its final put with call_rcu(). cleanup_net() runs the per-net exit methods and waits for outstanding RCU callbacks with rcu_barrier() before freeing namespace storage. Unlike ns.ns_id, net_cookie is also available and initialized during setup_net() in older stable kernels, making the change straightforward to backport to v5.15 and later.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 linux6.1.106-1, 6.1.106-2, 6.1.106-3
  • Debian:13 linux6.12.100-1, 6.12.101-1, 6.12.105-1
  • Debian:14 linux6.12.100-1, 6.12.101-1, 6.12.105-1
  • linux kernelversion unspecified
  • vendor Linux Linuxversion unspecified

How to fix CVE-2026-99201

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-99201. EPSS is 0.17%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with 6.1.106-1, 6.1.106-2, 6.1.106-3, 6.12.100-1, 6.12.101-1, 6.12.105-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian securityJenkins security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 28, 2026 · Tenable CVE Database

    Detected

    In the Linux kernel, the following vulnerability has been resolved: netlink: avoid hashing the network namespace pointer The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/netlink and socket diagnostics expose the table's bucket order. By binding and rebinding chosen NETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal buck

  2. Oct 28, 2026 · Trivy Vulnerability DB

    Updated

    In the Linux kernel, the following vulnerability has been resolved: netlink: avoid hashing the network namespace pointer The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/netlink and socket diagnostics expose the table's bucket order. By binding and rebinding chosen NETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal buck

Sources

  • BSI CERT-BundGovernment advisoryCVE-2026-99201

    Linux Kernel: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

    wid.cert-bund.de
  • CVE.orgVulnerability recordCVE-2026-99201

    In the Linux kernel, the following vulnerability has been resolved: netlink: avoid hashing the network namespace pointer The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/netlink and socket diagnostics expose the table's bu

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-99201

    30-day exploitation probability 0.17%

    first.org
  • Linux Kernel CVEVendor advisoryCVE-2026-99201

    From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: netlink: avoid hashing the network namespace pointer The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/net

    git.kernel.org
  • Tenable CVE DatabaseVulnerability recordCVE-2026-99201

    In the Linux kernel, the following vulnerability has been resolved: netlink: avoid hashing the network namespace pointer The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/netlink and socket diagnostics expose the table's bucket order. By binding and rebinding chosen NETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal buck

    tenable.com
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-99201
    osv.dev

References

Freshness

Last verified in this catalog Oct 31, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 31, 2026
  • BSI CERT-BundOct 30, 2026
  • CVE.orgOct 29, 2026
  • Trivy Vulnerability DBOct 28, 2026
  • Linux Kernel CVEOct 28, 2026
  • Tenable CVE DatabaseOct 28, 2026