UBUNTU-CVE-2026-64531
In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reject oversized nested action attrs Open vSwitch stores generated flow actions as nlattrs, whose nla_len field is u16. Commit a1e64addf3ff ("net: openvswitch: remove misbehaving actions length check") allowed the total sw_flow_actions stream to grow beyond 64 KiB, which is valid, but also removed the last guard preventing a generated nested action attribute from exceeding U16_MAX. An oversized generated container can thus be closed with a truncated nla_len. A later dump or teardown then walks a structurally different stream than the one that was validated. In particular, an oversized nested CLONE/CT action may cause subsequent bytes in the generated stream to be interpreted as independent actions. Keep the larger total-action-stream behavior, but make nested action close reject generated containers that do not fit in nla_len, and return the error through all callers. For recursive SAMPLE, CLONE, DEC_TTL, and CHECK_PKT_LEN builders, trim resource-owning action-list tails in reverse construction order before discarding failed wrappers, so resources copied into the rejected tails are released before the wrappers are removed. Most failed outer wrappers are discarded by truncating actions_len after child resources have been released. CHECK_PKT_LEN also trims its parent after branch resources are gone. SET/TUNNEL close failures unwind their known tun_dst ownership directly, and SET_TO_MASKED has no external ownership and truncates on close failure.
02 / AFFECTED SOFTWARE
Affected packages
11 explicit affected versions
6 explicit affected versions
89 explicit affected versions
50 explicit affected versions
6 explicit affected versions
37 explicit affected versions
12 explicit affected versions
19 explicit affected versions
10 explicit affected versions
6 explicit affected versions
100 explicit affected versions
61 explicit affected versions
24 explicit affected versions
5 explicit affected versions
85 explicit affected versions
84 explicit affected versions
86 explicit affected versions
76 explicit affected versions
10 explicit affected versions
39 explicit affected versions
26 explicit affected versions
90 explicit affected versions
7 explicit affected versions
84 explicit affected versions
42 explicit affected versions
13 explicit affected versions
46 explicit affected versions
35 explicit affected versions
3 explicit affected versions
51 explicit affected versions
50 explicit affected versions
18 explicit affected versions
42 explicit affected versions
3 explicit affected versions
64 explicit affected versions
47 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
54 explicit affected versions
1 explicit affected versions
21 explicit affected versions
9 explicit affected versions
16 explicit affected versions
10 explicit affected versions
10 explicit affected versions
50 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
14 explicit affected versions
1 explicit affected versions
7 explicit affected versions
19 explicit affected versions
12 explicit affected versions
10 explicit affected versions
12 explicit affected versions
43 explicit affected versions
12 explicit affected versions
11 explicit affected versions
45 explicit affected versions
16 explicit affected versions
9 explicit affected versions
29 explicit affected versions
36 explicit affected versions
10 explicit affected versions
37 explicit affected versions
10 explicit affected versions
11 explicit affected versions
13 explicit affected versions
42 explicit affected versions
3 explicit affected versions
10 explicit affected versions
11 explicit affected versions
68 explicit affected versions
26 explicit affected versions
12 explicit affected versions
13 explicit affected versions
37 explicit affected versions
4 explicit affected versions
29 explicit affected versions
13 explicit affected versions
12 explicit affected versions
96 explicit affected versions
43 explicit affected versions
42 explicit affected versions
8 explicit affected versions
92 explicit affected versions
55 explicit affected versions
33 explicit affected versions
23 explicit affected versions
60 explicit affected versions
10 explicit affected versions
22 explicit affected versions
21 explicit affected versions
11 explicit affected versions
5 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
10 explicit affected versions
20 explicit affected versions
5 explicit affected versions
77 explicit affected versions
93 explicit affected versions
10 explicit affected versions
26 explicit affected versions
41 explicit affected versions
69 explicit affected versions
37 explicit affected versions
48 explicit affected versions
11 explicit affected versions
10 explicit affected versions
13 explicit affected versions
48 explicit affected versions
16 explicit affected versions
91 explicit affected versions
52 explicit affected versions
12 explicit affected versions
3 explicit affected versions
7 explicit affected versions
51 explicit affected versions
18 explicit affected versions
43 explicit affected versions
12 explicit affected versions
71 explicit affected versions
80 explicit affected versions
7 explicit affected versions
27 explicit affected versions
3 explicit affected versions
65 explicit affected versions
10 explicit affected versions
53 explicit affected versions
14 explicit affected versions
38 explicit affected versions
45 explicit affected versions
8 explicit affected versions
55 explicit affected versions
3 explicit affected versions
5 explicit affected versions
8 explicit affected versions
9 explicit affected versions
10 explicit affected versions
7 explicit affected versions
48 explicit affected versions
13 explicit affected versions
13 explicit affected versions
7 explicit affected versions
8 explicit affected versions
10 explicit affected versions
12 explicit affected versions
9 explicit affected versions
39 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
9 explicit affected versions
11 explicit affected versions
41 explicit affected versions
20 explicit affected versions
45 explicit affected versions
92 explicit affected versions
8 explicit affected versions
7 explicit affected versions
4 explicit affected versions
81 explicit affected versions
10 explicit affected versions
1 explicit affected versions
91 explicit affected versions
80 explicit affected versions
79 explicit affected versions
10 explicit affected versions
13 explicit affected versions
43 explicit affected versions
16 explicit affected versions
5 explicit affected versions
10 explicit affected versions
8 explicit affected versions
48 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
21 explicit affected versions
6 explicit affected versions
41 explicit affected versions
80 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reject oversized nested action attrs Open vSwitch stores generated flow actions as nlattrs, whose nla_len field is u16. Commit a1e64addf3ff ("net: openvswitch: remove misbehaving actions length check") allowed the total sw_flow_actions stream to grow beyond 64 KiB, which is valid, but also removed the last guard preventing a generated nested action attribute from exceeding U16_MAX. An oversized generated container can thus be closed with a truncated nla_len. A later dump or teardown then walks a structurally different stream than the one that was validated. In particular, an oversized nested CLONE/CT action may cause subsequent bytes in the generated stream to be interpreted as independent actions. Keep the larger total-action-stream behavior, but make nested action close reject generated containers that do not fit in nla_len, and return the error through all callers. For recursive SAMPLE, CLONE, DEC_TTL, and CHECK_PKT_LEN builders, trim resource-owning action-list tails in reverse construction order before discarding failed wrappers, so resources copied into the rejected tails are released before the wrappers are removed. Most failed outer wrappers are discarded by truncating actions_len after child resources have been released. CHECK_PKT_LEN also trims its parent after branch resources are gone. SET/TUNNEL close failures unwind their known tun_dst ownership directly, and SET_TO_MASKED has no external ownership and truncates on close failure.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/3f1f755366687d051174739fb99f7d560202f60b
- https://git.kernel.org/stable/c/1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe
- https://git.kernel.org/stable/c/3f1f755366687d051174739fb99f7d560202f60b
- https://git.kernel.org/stable/c/ab855641241387db062a5e41d9ad6b8561542572
- https://git.kernel.org/stable/c/c66bd2626c2764f23764ff0f8277f44a9cfe8349
- https://git.kernel.org/stable/c/d573250d228401f707f4dbc09d11227a6215ee5f
- https://git.kernel.org/stable/c/dbd14f736be02cfe73049bd801af89becd1a0749
- https://git.kernel.org/stable/c/f1efff8858403191361a01269c6fe8dd7f55a385
- https://ubuntu.com/security/CVE-2026-64531
- https://ubuntu.com/security/notices/USN-8643-1
- https://www.cve.org/CVERecord?id=CVE-2026-64531