CVE-2026-31700: In the Linux kernel, the following vulnerability has been resolved: net/packet: fix TOCTOU race on mmap'd vne

Q: How do I fix CVE-2026-31700?

linux kernel: upgrade to 6.6.136, 6.12.84, 6.18.25, 7.0.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-31700 being exploited?

CVE-2026-31700 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-2026-31700 affect?

CVE-2026-31700 affects linux kernel. Severity is high (CVSS 7.8). In the Linux kernel, the following vulnerability has been resolved: net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points directly into the mmap'd TX ring buffer

Q: How urgent is CVE-2026-31700?

Priority 33/100. High severity; On your watchlist

Routine

HIGH 7.8WATCHLISTUPGRADE

CVE-2026-31700 is a high-severity flaw (CVSS 7.8) 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: net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points directly into the mmap'd TX ring buffer shared with userspace. The kernel validates the header via __packet_snd_vnet_parse() but then re-reads all fields later in virtio_net_hdr_to_skb(). A concurrent userspace thread can modify the vnet_hdr fields

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 99%)
CISA exploited list	No
Weakness	CWE-362, CWE-367
Published	2026-05-01
Last modified	2026-10-19

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

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-01 14:16 UTCPublished CVE record published
2026-10-19 20:17 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 4.6 and < 6.6.136 · >= 6.7 and < 6.12.84 · >= 6.13 and < 6.18.25 · >= 6.19 and < 7.0.2 · 7.1 rc1 · 7.1 rc2

Fixed in: 6.6.136, 6.12.84, 6.18.25, 7.0.2

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-2026-31700?

linux kernel: upgrade to 6.6.136, 6.12.84, 6.18.25, 7.0.2. Exact commands for each OS are on this page.

Is CVE-2026-31700 being exploited?

CVE-2026-31700 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-2026-31700 affect?

CVE-2026-31700 affects linux kernel. Severity is high (CVSS 7.8). In the Linux kernel, the following vulnerability has been resolved: net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points directly into the mmap'd TX ring buffer

How urgent is CVE-2026-31700?

Priority 33/100. High severity; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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