Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9 openvswitch datapath.c ovs_vport_get_upcall_portids deserialization

CVSS Meta Temp Score
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CTI Interest Score
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4.9$0-$5k0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9. Impacted is the function ovs_vport_get_upcall_portids of the file net/openvswitch/datapath.c of the component openvswitch. Executing a manipulation can lead to deserialization. This vulnerability is tracked as CVE-2026-45840. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9 and classified as critical. This vulnerability affects the function ovs_vport_get_upcall_portids of the file net/openvswitch/datapath.c of the component openvswitch. The manipulation with an unknown input leads to a deserialization vulnerability. The CWE definition for the vulnerability is CWE-502. The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: openvswitch: cap upcall PID array size and pre-size vport replies The vport netlink reply helpers allocate a fixed-size skb with nlmsg_new(NLMSG_DEFAULT_SIZE, ...) but serialize the full upcall PID array via ovs_vport_get_upcall_portids(). Since ovs_vport_set_upcall_portids() accepts any non-zero multiple of sizeof(u32) with no upper bound, a CAP_NET_ADMIN user can install a PID array large enough to overflow the reply buffer, causing nla_put() to fail with -EMSGSIZE and hitting BUG_ON(err < 0). On systems with unprivileged user namespaces enabled (e.g., Ubuntu default), this is reachable via unshare -Urn since OVS vport mutation operations use GENL_UNS_ADMIN_PERM. kernel BUG at net/openvswitch/datapath.c:2414! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 1 UID: 0 PID: 65 Comm: poc Not tainted 7.0.0-rc7-00195-geb216e422044 #1 RIP: 0010:ovs_vport_cmd_set+0x34c/0x400 Call Trace: <TASK> genl_family_rcv_msg_doit (net/netlink/genetlink.c:1116) genl_rcv_msg (net/netlink/genetlink.c:1194) netlink_rcv_skb (net/netlink/af_netlink.c:2550) genl_rcv (net/netlink/genetlink.c:1219) netlink_unicast (net/netlink/af_netlink.c:1344) netlink_sendmsg (net/netlink/af_netlink.c:1894) __sys_sendto (net/socket.c:2206) __x64_sys_sendto (net/socket.c:2209) do_syscall_64 (arch/x86/entry/syscall_64.c:63) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) </TASK> Kernel panic - not syncing: Fatal exception Reject attempts to set more PIDs than nr_cpu_ids in ovs_vport_set_upcall_portids(), and pre-compute the worst-case reply size in ovs_vport_cmd_msg_size() based on that bound, similar to the existing ovs_dp_cmd_msg_size(). nr_cpu_ids matches the cap already used by the per-CPU dispatch configuration on the datapath side (ovs_dp_cmd_fill_info() serialises at most nr_cpu_ids PIDs), so the two sides stay consistent.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-45840 since 05/13/2026. The exploitation appears to be difficult. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/22/2026).

The vulnerability scanner Nessus provides a plugin with the ID 321868 (Debian dsa-6355 : ata-modules-6.12.90+deb13-armmp-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.141, 6.12.91, 6.18.33, 7.0.10 or 7.1-rc1 eliminates this vulnerability. Applying the patch f9ef3db77a383d66847fd082c2b437d8ae4d9c63/f99ac36b5d7c719d08a69fcdecce40f78a874e15/fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704/1d6c02b86329883aa467a3a61f8d34369db73a2f/2091c6aa0df6aba47deb5c8ab232b1cb60af3519 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (321868), EUVD (EUVD-2026-32166) and CERT Bund (WID-SEC-2026-1691). Once again VulDB remains the best source for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • SUSE Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • Ubuntu Linux

Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.9

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Deserialization
CWE: CWE-502 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 321868
Nessus Name: Debian dsa-6355 : ata-modules-6.12.90+deb13-armmp-di - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.141/6.12.91/6.18.33/7.0.10/7.1-rc1
Patch: f9ef3db77a383d66847fd082c2b437d8ae4d9c63/f99ac36b5d7c719d08a69fcdecce40f78a874e15/fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704/1d6c02b86329883aa467a3a61f8d34369db73a2f/2091c6aa0df6aba47deb5c8ab232b1cb60af3519

Timelineinfo

05/13/2026 CVE reserved
05/27/2026 +14 days Advisory disclosed
05/27/2026 +0 days VulDB entry created
07/22/2026 +56 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-45840 (🔒)
GCVE (CVE): GCVE-0-2026-45840
GCVE (VulDB): GCVE-100-366052
EUVD: 🔒
CERT Bund: WID-SEC-2026-1691 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/27/2026 13:46
Updated: 07/22/2026 13:32
Changes: 05/27/2026 13:46 (60), 05/27/2026 15:53 (7), 05/27/2026 16:01 (1), 06/15/2026 12:29 (1), 06/21/2026 21:51 (2), 06/26/2026 21:05 (12), 07/22/2026 13:32 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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