5.5

CVE-2026-45840: linux

CVSS: 5.5v3.1MediumModified
AliasesUBUNTU-CVE-2026-45840DEBIAN-CVE-2026-45840
Published 27-05-2026Last modified 15-10-2026
Open JSON

Vulnerability summary

CVE-2026-45840 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.4% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.13%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 51 · Related 51
OPENSUSE-SU-2026:10954-1OPENSUSE-SU-2026:21388-1SUSE-SU-2026:22433-1SUSE-SU-2026:22436-1SUSE-SU-2026:22458-1SUSE-SU-2026:22460-1

Timeline

  1. 27-05-2026
    PublishedVulnerability first disclosed.
  2. 15-10-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.13%

Chance of exploitation in the next 30 days

Percentile

2%

Versus all other CVEs

30-day change

0.00 pp

From 0.13% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.13%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Ubuntu166 products
  • linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-136.136 | < 7.0.0-28.28
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1061.64 | < 7.0.0-1009.9
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < 8d59b80e69dddb665eb2de36e62859ab2073470e | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < d9e47e29aacb9f8a9d59feb6ab5b128a9bbb40b0 | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < b39f763d720d623218bc1d95ace6855d7b474e81 | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < f9ef3db77a383d66847fd082c2b437d8ae4d9c63 | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < f99ac36b5d7c719d08a69fcdecce40f78a874e15 | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704 | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < 1d6c02b86329883aa467a3a61f8d34369db73a2f | ≥ 5cd667b0a4567048bb555927d6ee564f4e5620a9, < 2091c6aa0df6aba47deb5c8ab232b1cb60af3519 | 3.17
  • linux_kernel≥ 3.17, < 5.10.258 | ≥ 5.11, < 5.15.209 | ≥ 5.16, < 6.1.175 | ≥ 6.2, < 6.6.141 | ≥ 6.7, < 6.12.91 | ≥ 6.13, < 6.18.33 | ≥ 6.19, < 7.0.10
Debian1 product
  • linux< 6.1.176-1 | < 6.12.94-1 | < 7.0.10-1

3 vendors · 169 products

References

52 links
Show all 52 references