# CVE-2026-46300: Linux Kernel out-of-bounds write in skbuff coalescing

Source: https://junglewise.ai/threats/cve-2026-46300-linux-kernel-out-of-bounds-write-in-skbuff-coalescing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-23. Updated: 2026-05-26  
License: CC BY 4.0 with a link back

CVE-2026-46300 · Severity: critical · CVSS 7.8 · Exploited in the wild · Published 2026-05-23

A vulnerability in the Linux kernel's networking subsystem could allow an attacker to cause data corruption or potentially gain unauthorized access. The issue occurs when the system incorrectly handles shared memory fragments during network data processing, leading to situations where encrypted data might be overwritten or improperly accessed. This affects the integrity and confidentiality of data handled by the system's network stack.

Technologies: [Amazon AWS](https://junglewise.ai/threats/technologies/aws), [Google Cloud Platform](https://junglewise.ai/threats/technologies/google-cloud-platform), [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Amazon](https://junglewise.ai/threats/vendors/amazon), [Google](https://junglewise.ai/threats/vendors/google), [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-46300 exploited in the wild?** Yes. CVE-2026-46300 is known to be exploited in the wild, first recorded on 28 October 2026. Treat it as urgent.

**How severe is CVE-2026-46300?** Critical severity, with a CVSS score of 7.8, published 23 May 2026.

**Which products and versions are affected?** Linux Kernel Versions supporting ESP-in-TCP (espintcp) module.

**Is there a fix for CVE-2026-46300?** A patch was published on 2026-05-23: Fixes merged into various stable kernel branches Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-46300 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-46300?** Check whether you run Amazon AWS, Google Cloud Platform or Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in the Linux kernel's skbuff management where the skb_try_coalesce() function fails to propagate the SKBFL_SHARED_FRAG (or SKBTX_SHARED_FRAG in older versions) flag when attaching paged fragments. This flag indicates that fragments are externally owned or page-cache-backed. When this marker is lost, subsequent in-place writers—specifically the ESP (Encapsulating Security Payload) input path—may incorrectly assume the data is safe to modify in place. This can result in the kernel decrypting data directly over page-cache backed fragments, leading to an out-of-bounds write (CWE-787) or memory corruption. The issue has been resolved by ensuring the shared-fragment bit is propagated during fragment transfers.

## Affected products

- Linux Linux Kernel 3.9 to 5.10.257, 5.11 to 5.15.208, 5.16 to 6.1.174, 6.2 to 6.6.141, 6.7 to 6.12.91, 6.13 to 6.18.33, 6.19 to 7.0.10

## Identifiers

- CVE-2026-46300
- CVE-2026-43284

## Timeline

- 2026-05-13: disclosed: Vulnerability reported by William Bowling
- 2026-05-23: patched: Fixes merged into various stable kernel branches
- 2026-05-23: advisory: Initial NVD publication

## References

- [https://git.kernel.org/stable/c/2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c](https://git.kernel.org/stable/c/2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c)
- [https://git.kernel.org/stable/c/3599e6b3cc1ada96883d496a50a210d3afbb6987](https://git.kernel.org/stable/c/3599e6b3cc1ada96883d496a50a210d3afbb6987)
- [https://git.kernel.org/stable/c/3884358a9286b17f389a72b1426fc4547c23c111](https://git.kernel.org/stable/c/3884358a9286b17f389a72b1426fc4547c23c111)
- [https://git.kernel.org/stable/c/3bd9e113d50034db99d7ef69fd8e5242d15e414a](https://git.kernel.org/stable/c/3bd9e113d50034db99d7ef69fd8e5242d15e414a)
- [https://git.kernel.org/stable/c/760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e](https://git.kernel.org/stable/c/760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e)
- [https://git.kernel.org/stable/c/78bf6b6bb19541d19fbda6242e7cfe2c682763c0](https://git.kernel.org/stable/c/78bf6b6bb19541d19fbda6242e7cfe2c682763c0)
- [https://git.kernel.org/stable/c/9d3e5fd19fe1063bf607219e8562fbd567b8e8d5](https://git.kernel.org/stable/c/9d3e5fd19fe1063bf607219e8562fbd567b8e8d5)

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