// For flags

CVE-2026-31495

netfilter: ctnetlink: use netlink policy range checks

Severity Score

5.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: use netlink policy range checks Replace manual range and mask validations with netlink policy
annotations in ctnetlink code paths, so that the netlink core rejects
invalid values early and can generate extack errors. - CTA_PROTOINFO_TCP_STATE: reject values > TCP_CONNTRACK_SYN_SENT2 at policy level, removing the manual >= TCP_CONNTRACK_MAX check.
- CTA_PROTOINFO_TCP_WSCALE_ORIGINAL/REPLY: reject values > TCP_MAX_WSCALE (14). The normal TCP option parsing path already clamps to this value, but the ctnetlink path accepted 0-255, causing undefined behavior when used as a u32 shift count.
- CTA_FILTER_ORIG_FLAGS/REPLY_FLAGS: use NLA_POLICY_MASK with CTA_FILTER_F_ALL, removing the manual mask checks.
- CTA_EXPECT_FLAGS: use NLA_POLICY_MASK with NF_CT_EXPECT_MASK, adding a new mask define grouping all valid expect flags. Extracted from a broader nf-next patch by Florian Westphal, scoped to
ctnetlink for the fixes tree.

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2026-03-09 CVE Reserved
  • 2026-04-22 CVE Published
  • 2026-04-28 CVE Updated
  • 2026-04-28 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 5.10.253
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 5.10.253"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 5.15.203
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 5.15.203"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 6.1.168
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 6.1.168"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 6.6.131
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 6.6.131"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 6.12.80
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 6.12.80"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 6.18.21
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 6.18.21"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 6.19.11
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 6.19.11"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.22 < 7.0
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.22 < 7.0"
en
Affected