CVE-2026-43329: netfilter: flowtable: strictly check for maximum number of actions
Vulnerability summary
CVE-2026-43329 is a high (CVSS 7.8) Heap-based Buffer Overflow vulnerability in linux. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.4% of scored vulnerabilities.
Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 49 · Related 30Timeline
- 08-05-2026PublishedVulnerability first disclosed.
- 19-10-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.18%
Chance of exploitation in the next 30 days
Percentile
7%
Versus all other CVEs
30-day change
Decrease -0.01 pp
From 0.19% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-122Heap-based Buffer OverflowThe product writes past the end of a buffer that was allocated on the heap.
- CWE-770Allocation of Resources Without Limits or ThrottlingThe product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu145 products
- linux< 5.15.0-186.196 | < 6.8.0-136.136 | All versions (No fix recorded)
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 5.15.0-1112.119 | < 6.8.0-1061.64 | All versions (No fix recorded)
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < ead66c77303f760f6c30be96e2e20d5a77cef614 | ≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < fe9018d3e94329f1951b00805a8640bc06f56ead | ≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < 5382bb03e9c33b089d60788478b922a2dca284cc | ≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < 57c78bd2e2dd08897acd35b2bf8bcef322e36f5e | ≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < 504c9456699dcf4d15195ef34a0fa94a80bfc877 | ≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < 879959a7a2be814dd57568655eafa3d8f4d0309e | ≥ c29f74e0df7a02b8303bcdce93a7c0132d62577a, < 76522fcdbc3a02b568f5d957f7e66fc194abb893 | 5.5
- linux_kernel≥ 5.5, < 5.15.203 | ≥ 5.16, < 6.1.168 | ≥ 6.2, < 6.6.134 | ≥ 6.7, < 6.12.81 | ≥ 6.13, < 6.18.22 | ≥ 6.19, < 6.19.12 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6
Debian1 product
- linux< 6.1.170-1 | < 6.12.85-1 | < 6.19.12-1
3 vendors · 148 products
