CVE-2026-45840: In the Linux kernel, the following vulnerability has been resolved: openvswitch: cap upcall PID array size an

Q: How do I fix CVE-2026-45840?

linux kernel: upgrade to 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10. Exact commands for each OS are on this page.

Q: Is CVE-2026-45840 being exploited?

CVE-2026-45840 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-45840 affect?

CVE-2026-45840 affects linux kernel. Severity is medium (CVSS 5.5). 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 se

Q: How urgent is CVE-2026-45840?

Priority 25/100. On your watchlist

Routine

MEDIUM 5.5WATCHLISTUPGRADE

CVE-2026-45840 is a medium-severity flaw (CVSS 5.5) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 P

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 97%)
CISA exploited list	No
Published	2026-05-27
Last modified	2026-10-15

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-27 11:16 UTCPublished CVE record published
2026-10-15 02:19 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 3.17 and < 5.10.258 · >= 5.11 and < 5.15.209 · >= 5.16 and < 6.1.175 · >= 6.2 and < 6.6.141 · >= 6.7 and < 6.12.91 · >= 6.13 and < 6.18.33 · >= 6.19 and < 7.0.10

Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-45840?

linux kernel: upgrade to 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10. Exact commands for each OS are on this page.

Is CVE-2026-45840 being exploited?

CVE-2026-45840 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-45840 affect?

CVE-2026-45840 affects linux kernel. Severity is medium (CVSS 5.5). 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 se

How urgent is CVE-2026-45840?

Priority 25/100. On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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