Description
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.
Affected products
linux: linux kernel
References10
- git.kernel.org/stable/c/1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe Patch
- git.kernel.org/stable/c/3f1f755366687d051174739fb99f7d560202f60b Patch
- git.kernel.org/stable/c/ab855641241387db062a5e41d9ad6b8561542572 Patch
- git.kernel.org/stable/c/c66bd2626c2764f23764ff0f8277f44a9cfe8349 Patch
- git.kernel.org/stable/c/d573250d228401f707f4dbc09d11227a6215ee5f Patch
- git.kernel.org/stable/c/dbd14f736be02cfe73049bd801af89becd1a0749 Patch
- git.kernel.org/stable/c/f1efff8858403191361a01269c6fe8dd7f55a385 Patch
- www.openwall.com/lists/oss-security/2026/07/28/8 Mailing List
- www.openwall.com/lists/oss-security/2026/07/31/17 Mailing List
- www.openwall.com/lists/oss-security/2026/08/01/1 Mailing List
Metrics
- CVSS 3.1
-
7.8
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 39 · as of 13 November 2026
- CWE
- CWE-190
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