CVE-2026-43329

netfilter: flowtable: strictly check for maximum number of actions

HIGH
7.8
CVSS Score
Published: May 8, 2026 at 01:31 PM UTC
Updated: October 19, 2026 at 08:18 PM UTC
3 products affected across 2 vendorsLinux KernelEnterprise LinuxOpenShift Container Platform

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Severity
HIGH7.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: strictly check for maximum number of actions The maximum number of flowtable hardware offload actions in IPv6 is: * ethernet mangling (4 payload actions, 2 for each ethernet address) * SNAT (4 payload actions) * DNAT (4 payload actions) * Double VLAN (4 vlan actions, 2 for popping vlan, and 2 for pushing) for QinQ. * Redirect (1 action) Which makes 17, while the maximum is 16. But act_ct supports for tunnels actions too. Note that payload action operates at 32-bit word level, so mangling an IPv6 address takes 4 payload actions. Update flow_action_entry_next() calls to check for the maximum number of supported actions. While at it, rise the maximum number of actions per flow from 16 to 24 so this works fine with IPv6 setups.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.16 ≤ v < 6.1.1685.5 ≤ v < 5.15.2036.13 ≤ v < 6.18.226.19 ≤ v < 6.19.126.2 ≤ v < 6.6.1346.7 ≤ v < 6.12.817.07.0 rc17.0 rc27.0 rc37.0 rc47.0 rc57.0 rc6c29f74e0df7a02b8303bcdce93a7c0132d62577a
Vendor states this is fixed in 504c9456699dcf4d15195ef34a0fa94a80bfc877 (fixed)
Vendor states this is fixed in 5382bb03e9c33b089d60788478b922a2dca284cc (fixed)
Vendor states this is fixed in 57c78bd2e2dd08897acd35b2bf8bcef322e36f5e (fixed)
Vendor states this is fixed in 76522fcdbc3a02b568f5d957f7e66fc194abb893 (fixed)
Vendor states this is fixed in 879959a7a2be814dd57568655eafa3d8f4d0309e (fixed)
Vendor states this is fixed in ead66c77303f760f6c30be96e2e20d5a77cef614 (fixed)
Vendor states this is fixed in fe9018d3e94329f1951b00805a8640bc06f56ead (fixed)
Vendor states this is fixed in 5.15.203 (unaffected)
Vendor states this is fixed in 5.5 (unaffected)
Vendor states this is fixed in 6.1.168 (unaffected)
Vendor states this is fixed in 6.12.81 (unaffected)
Vendor states this is fixed in 6.18.22 (unaffected)
Vendor states this is fixed in 6.19.12 (unaffected)
Vendor states this is fixed in 6.6.134 (unaffected)
Vendor states this is fixed in 7.0 (unaffected)
Vendor states this is fixed in 0:4.18.0-305.197.1.el8_4 (unaffected)
Vendor states this is fixed in 0:4.18.0-372.198.1.el8_6 (unaffected)
Vendor states this is fixed in 0:4.18.0-477.150.1.el8_8 (unaffected)
Vendor states this is fixed in 0:4.18.0-553.134.1.el8_10 (unaffected)
Vendor states this is fixed in 0:4.18.0-553.134.1.rt7.475.el8_10 (unaffected)
Vendor states this is fixed in 0:5.14.0-284.178.1.el9_2 (unaffected)
Vendor states this is fixed in 0:5.14.0-284.178.1.rt14.463.el9_2 (unaffected)
Vendor states this is fixed in 0:5.14.0-427.134.1.el9_4 (unaffected)
Vendor states this is fixed in 0:5.14.0-570.125.1.el9_6 (unaffected)
Vendor states this is fixed in 0:5.14.0-687.19.1.el9_8 (unaffected)
Vendor states this is fixed in 0:6.12.0-211.20.1.el10_2 (unaffected)
Vendor states this is fixed in 0:6.12.0-55.84.1.el10_0 (unaffected)
Vendor states this is fixed in 10 (unaffected)
Vendor states this is fixed in 6 (unaffected)
Vendor states this is fixed in 7 (unaffected)
Vendor states this is fixed in 4.19.9.6.202607220857-0 (unaffected)
Vendor states this is fixed in 4.20.9.6.202607221038-0 (unaffected)
Vendor states this is fixed in 4.21.9.6.202607221317-0 (unaffected)
Vendor states this is fixed in 4.22.9.8.202607152026-0 (unaffected)
Vendor states this is fixed in 412.86.202607211933-0 (unaffected)
Vendor states this is fixed in 413.92.202608111330-0 (unaffected)
Vendor states this is fixed in 414.92.202607210313-0 (unaffected)
Vendor states this is fixed in 415.92.202608180329-0 (unaffected)
Vendor states this is fixed in 416.94.202608150307-0 (unaffected)
Vendor states this is fixed in 417.94.202607240132-0 (unaffected)
Vendor states this is fixed in 418.94.202607211754-0 (unaffected)

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHLinux
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfoCWE-770CWE-122

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