CVE-2026-64531 is a vulnerability in Linux Kernel
Published on July 27, 2026
net: openvswitch: reject oversized nested action attrs
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.
Products Associated with CVE-2026-64531
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Affected Versions
Linux:- Version 057dbc5b72e9fcac439cd561c3a539b8a0edeb92 and below ab855641241387db062a5e41d9ad6b8561542572 is affected.
- Version 2532adbfe917c0e71dba2650ffc6efe396314c87 and below c66bd2626c2764f23764ff0f8277f44a9cfe8349 is affected.
- Version 4b1a0ee6164c7204c68ab5a9c48c07bfe8852485 and below d573250d228401f707f4dbc09d11227a6215ee5f is affected.
- Version e6610f9c08b4c04cf7949c10fc246c071d00e935 and below f1efff8858403191361a01269c6fe8dd7f55a385 is affected.
- Version a1e64addf3ff9257b45b78bc7d743781c3f41340 and below dbd14f736be02cfe73049bd801af89becd1a0749 is affected.
- Version a1e64addf3ff9257b45b78bc7d743781c3f41340 and below 1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe is affected.
- Version a1e64addf3ff9257b45b78bc7d743781c3f41340 and below 3f1f755366687d051174739fb99f7d560202f60b is affected.
- Version 6b099d285d7ed324494b6d684f377aa103856118 is affected.
- Version 5.15.180 and below 5.15.212 is affected.
- Version 6.1.132 and below 6.1.178 is affected.
- Version 6.6.84 and below 6.6.145 is affected.
- Version 6.12.20 and below 6.12.97 is affected.
- Version 6.13.8 and below 6.14 is affected.
- Version 6.14 is affected.
- Before 6.14 is unaffected.
- Version 5.15.212, <= 5.15.* is unaffected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.97, <= 6.12.* is unaffected.
- Version 6.18.40, <= 6.18.* is unaffected.
- Version 7.1.5, <= 7.1.* is unaffected.
- Version 7.2-rc4, <= * is unaffected.