# What is CVE-2026-46300?

> CVE-2026-46300 is a high-severity flaw (CVSS 7.8) in Linux kernel, published on 23 May 2026. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 10%. If you run an affected version, patch it first.

Canonical page: https://www.edgeprotect.io/what-is/cve-2026-46300

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **EdgeProtect risk score:** 75 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.8 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 10% (latest exploit-likelihood forecast)
- **Published:** 23 May 2026
- **Record last updated:** 8 September 2026
- **Main product:** Linux kernel
- **Affected products:** 1

## What is CVE-2026-46300? In plain terms

An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official description

In the Linux kernel, the following vulnerability has been resolved:

net: skbuff: preserve shared-frag marker during coalescing

skb_try_coalesce() can attach paged frags from @from to @to.  If @from
has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same
externally-owned or page-cache-backed frags, but the shared-frag marker
is currently lost.

That breaks the invariant relied on by later in-place writers.  In
particular, ESP input checks skb_has_shared_frag() before deciding
whether an uncloned nonlinear skb can skip skb_cow_data().  If TCP
receive coalescing has moved shared frags into an unmarked skb, ESP can
see skb_has_shared_frag() as false and decrypt in place over page-cache
backed frags.

Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged
frags.  The tailroom copy path does not need the marker because it copies
bytes into @to's linear data rather than transferring frag descriptors.

### What kind of flaw is it?

- CWE-787: Out-of-bounds Write
- CWE-123: Write-what-where Condition

### How an attack on it works

- Where an attacker can be: Already on the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2026-46300 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 10%.

Exploit likelihood over the last 7 days: 2.4%, 2.4%, 2.4%, 10%, 10%, 10%, 10%.

### Timeline

- 23 May 2026: Published
- 8 September 2026: Record last updated
- 29 October 2026: Added to the known-exploited list

### How EdgeProtect ranks it

CVE-2026-46300 scores **75 out of 100 (High)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: key context
- Real threat activity around it: key context

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2026-46300?

The published record lists 1 product. Versions are as published: "5.11 to before 5.15.208" means from 5.11 up to, but not including, 5.15.208.

- [Linux kernel](https://www.edgeprotect.io/product/linux/linux_kernel) by [Linux](https://www.edgeprotect.io/vendors/linux) (Operating system): 3.9 to 5.10.257, 5.11 to before 5.15.208, 5.16 to before 6.1.174, 6.2 to before 6.6.141, 6.7 to before 6.12.91, 6.13 to before 6.18.33, 6.19 to before 7.0.10, 7.1-rc1, 7.1-rc2, 7.1-rc3, 7.1-rc4

## How do I fix CVE-2026-46300?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? EdgeProtect can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [git.kernel.org](https://git.kernel.org/stable/c/2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/3599e6b3cc1ada96883d496a50a210d3afbb6987) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/3884358a9286b17f389a72b1426fc4547c23c111) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/3bd9e113d50034db99d7ef69fd8e5242d15e414a) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/78bf6b6bb19541d19fbda6242e7cfe2c682763c0) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/9d3e5fd19fe1063bf607219e8562fbd567b8e8d5) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/f84eca5817390257cef78013d0112481c503b4a3) (Patch)
- [openwall.com](http://www.openwall.com/lists/oss-security/2026/05/13/5) (Mailing list)
- [openwall.com](http://www.openwall.com/lists/oss-security/2026/05/21/11) (Mailing list)
- [openwall.com](http://www.openwall.com/lists/oss-security/2026/05/21/12) (Mailing list)
- [openwall.com](http://www.openwall.com/lists/oss-security/2026/05/21/13) (Mailing list)
- [access.redhat.com](https://access.redhat.com/errata/RHBA-2026:20032)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19521)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19540)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19568)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19569)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19664)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19666)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19705)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19711)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:19875)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20051)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20054)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20087)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20129)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20130)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20299)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:20593)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:21656)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:21690)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:21695)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:21702)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23233)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23240)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23245)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23468)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23469)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23470)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:23471)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:24814)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:25044)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:28887)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:33486)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:34098)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2026-46300)
- [bugzilla.redhat.com](https://bugzilla.redhat.com/show_bug.cgi?id=2477015)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-082556.html)
- [security.access.redhat.com](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46300.json)

## Questions

### What is CVE-2026-46300?

CVE-2026-46300 is a high-severity flaw in Linux kernel, published on 23 May 2026. An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2026-46300?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2026-46300 is 75 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2026-46300 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 10%.

### Which versions does CVE-2026-46300 affect?

For Linux kernel: 3.9 to 5.10.257, 5.11 to before 5.15.208, 5.16 to before 6.1.174, 6.2 to before 6.6.141, 6.7 to before 6.12.91, 6.13 to before 6.18.33 and 5 more.

### How do I fix CVE-2026-46300?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2026-46300 affect you?

EdgeProtect keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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