net: openvswitch: fix middle attribute validation in push_nsh() action

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-68785
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-13 16:15:58 UTC
Updated2026-07-30 06:24:44 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: openvswitch: fix middle attribute validation in push_nsh() action The push_nsh() action structure looks like this: OVS_ACTION_ATTR_PUSH_NSH(OVS_KEY_ATTR_NSH(OVS_NSH_KEY_ATTR_BASE,...)) The outermost OVS_ACTION_ATTR_PUSH_NSH attribute is OK'ed by the nla_for_each_nested() inside __ovs_nla_copy_actions(). The innermost OVS_NSH_KEY_ATTR_BASE/MD1/MD2 are OK'ed by the nla_for_each_nested() inside nsh_key_put_from_nlattr(). But nothing checks if the attribute in the middle is OK. We don't even check that this attribute is the OVS_KEY_ATTR_NSH. We just do a double unwrap with a pair of nla_data() calls - first time directly while calling validate_push_nsh() and the second time as part of the nla_for_each_nested() macro, which isn't safe, potentially causing invalid memory access if the size of this attribute is incorrect. The failure may not be noticed during validation due to larger netlink buffer, but cause trouble later during action execution where the buffer is allocated exactly to the size: BUG: KASAN: slab-out-of-bounds in nsh_hdr_from_nlattr+0x1dd/0x6a0 [openvswitch] Read of size 184 at addr ffff88816459a634 by task a.out/22624 CPU: 8 UID: 0 PID: 22624 6.18.0-rc7+ #115 PREEMPT(voluntary) Call Trace: <TASK> dump_stack_lvl+0x51/0x70 print_address_description.constprop.0+0x2c/0x390 kasan_report+0xdd/0x110 kasan_check_range+0x35/0x1b0 __asan_memcpy+0x20/0x60 nsh_hdr_from_nlattr+0x1dd/0x6a0 [openvswitch] push_nsh+0x82/0x120 [openvswitch] do_execute_actions+0x1405/0x2840 [openvswitch] ovs_execute_actions+0xd5/0x3b0 [openvswitch] ovs_packet_cmd_execute+0x949/0xdb0 [openvswitch] genl_family_rcv_msg_doit+0x1d6/0x2b0 genl_family_rcv_msg+0x336/0x580 genl_rcv_msg+0x9f/0x130 netlink_rcv_skb+0x11f/0x370 genl_rcv+0x24/0x40 netlink_unicast+0x73e/0xaa0 netlink_sendmsg+0x744/0xbf0 __sys_sendto+0x3d6/0x450 do_syscall_64+0x79/0x2c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> Let's add some checks that the attribute is properly sized and it's the only one attribute inside the action. Technically, there is no real reason for OVS_KEY_ATTR_NSH to be there, as we know that we're pushing an NSH header already, it just creates extra nesting, but that's how uAPI works today. So, keeping as it is.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS: 0.001320000 probability, percentile 0.032130000 (date 2026-08-01)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 d0c135b8bbbcf92836068fd395bebeb7ae6c7bef git Not specified
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 3bc2efff20a38b2c7ca18317649715df0dd62ced git Not specified
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 1b569db9c2f28b599e40050524aae5f7332bc294 git Not specified
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 10ffc558246f2c75619aedda0921906095e46702 git Not specified
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 2ecfc4433acdb149eafd7fb22d7fd4adf90b25e9 git Not specified
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 c999153bfb2d1d9b295b7010d920f2a7c6d7595f git Not specified
CNA Linux Linux affected b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3 5ace7ef87f059d68b5f50837ef3e8a1a4870c36e git Not specified
CNA Linux Linux affected 4.15 Not specified
CNA Linux Linux unaffected 4.15 semver Not specified
CNA Linux Linux unaffected 5.10.248 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.198 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.160 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.120 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.64 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.3 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/5ace7ef87f059d68b5f50837ef3e8a1a4870c36e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/10ffc558246f2c75619aedda0921906095e46702 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3bc2efff20a38b2c7ca18317649715df0dd62ced 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1b569db9c2f28b599e40050524aae5f7332bc294 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c999153bfb2d1d9b295b7010d920f2a7c6d7595f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d0c135b8bbbcf92836068fd395bebeb7ae6c7bef 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2ecfc4433acdb149eafd7fb22d7fd4adf90b25e9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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