# What is CVE-2026-43500?

> CVE-2026-43500 is a high-severity flaw (CVSS 7.8) in Linux kernel, published on 11 May 2026. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 94%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.edgeprotect.io/what-is/cve-2026-43500

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **EdgeProtect risk score:** 70 out of 100 (High); action: Patch now. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.8 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 94% (latest exploit-likelihood forecast)
- **Published:** 11 May 2026
- **Record last updated:** 24 August 2026
- **Main product:** Linux kernel
- **Affected products:** 1

## What is CVE-2026-43500? 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:

rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE
handler in rxrpc_verify_response() copy the skb to a linear one before
calling into the security ops only when skb_cloned() is true.  An skb
that is not cloned but still carries externally-owned paged fragments
(e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via
__ip_append_data, or a chained skb_has_frag_list()) falls through to
the in-place decryption path, which binds the frag pages directly into
the AEAD/skcipher SGL via skb_to_sgvec().

Extend the gate to also unshare when skb_has_frag_list() or
skb_has_shared_frag() is true.  This catches the splice-loopback vector
and other externally-shared frag sources while preserving the
zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC
page_pool RX, GRO).  The OOM/trace handling already in place is reused.

### 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-2026-43500 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 94%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 2.6%, 2.6%, 94%, 94%, 94%, 94%, 94%.

### Timeline

- 11 May 2026: Published
- 29 May 2026: Exploit likelihood jumped
- 24 August 2026: Record last updated
- 25 September 2026: Exploit likelihood fell

### How EdgeProtect ranks it

CVE-2026-43500 scores **70 out of 100 (High)**, with the action "Patch now".

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-2026-43500?

The published record lists 1 product. Versions are as published: "after 5.3 to before 6.18.29" means every version up to, but not including, 6.18.29.

- [Linux kernel](https://www.edgeprotect.io/product/linux/linux_kernel) by [Linux](https://www.edgeprotect.io/vendors/linux) (Operating system): 5.3-rc7, 5.3-rc8, after 5.3 to before 6.18.29, 5.3, 6.19 to before 7.0.6, 7.1-rc1, 7.1-rc2

## How do I fix CVE-2026-43500?

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. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [git.kernel.org](https://git.kernel.org/stable/c/3eae0f4f9f7206a4801efa5e0235c25bbd5a412c) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/aa54b1d27fe0c2b78e664a34fd0fdf7cd1960d71) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/d45179f8795222ce858770dc619abe51f9d24411) (Patch)
- [git.kernel.org](https://git.kernel.org/stable/c/3711382a77342a9a1c3d2e7330dcfc7ea927f568)
- [git.kernel.org](https://git.kernel.org/stable/c/7c504ffab3efce8f7e4f463b314ae31030bdf18b)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2026-43500)
- [bugzilla.redhat.com](https://bugzilla.redhat.com/show_bug.cgi?id=2468273)
- [github.com](https://github.com/V4bel/dirtyfrag)
- [security.access.redhat.com](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43500.json)

## Questions

### What is CVE-2026-43500?

CVE-2026-43500 is a high-severity flaw in Linux kernel, published on 11 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-2026-43500?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2026-43500 is 70 out of 100, which is High. Its action is "Patch now". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2026-43500 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 94%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2026-43500 affect?

For Linux kernel: 5.3-rc7, 5.3-rc8, after 5.3 to before 6.18.29, 5.3, 6.19 to before 7.0.6, 7.1-rc1 and 1 more.

### How do I fix CVE-2026-43500?

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.

## Does CVE-2026-43500 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.

Start free (no card, nothing to install): https://www.edgeprotect.io/register
Book a demo: https://www.edgeprotect.io/contact