# CVE-2026-99284: Linux kernel shared-frag flag loss in skb_zerocopy

Source: https://junglewise.ai/threats/cve-2026-99284-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-07. Updated: 2026-11-07  
License: CC BY 4.0 with a link back

CVE-2026-99284 · Severity: info · Published 2026-11-07

The Linux kernel's skb_zerocopy() function transfers packet fragments without preserving a critical shared-memory marker. This allows unprivileged users to write into page-cache regions of root-owned read-only files when ESP decryption bypasses safety checks, potentially leading to privilege escalation or system compromise.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-99284 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99284 being exploited in the wild.

**How severe is CVE-2026-99284?** Informational severity, published 7 November 2026.

**Which products and versions are affected?** Linux Kernel Multiple versions through at least 6.x.

**Is there a fix for CVE-2026-99284?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-99284 attacked?** It is attacked over the network or with local access, in an operating system.

**Am I affected by CVE-2026-99284?** Check whether you run 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

The skb_zerocopy() function in net/core/skbuff.c copies fragment descriptors between packet buffers but fails to propagate the SKBFL_SHARED_FRAG flag, breaking the skb_has_shared_frag() check that ESP input handlers rely on to prevent in-place decryption on shared fragments. An unprivileged attacker can create packets through nfnetlink_queue or OpenVSwitch upcalls that bypass skb_cow_data() checks, leading to direct writes into kernel page-cache backing root-owned files. The fix adds a single flag propagation line during fragment transfer.

## Affected products

- Linux Linux Kernel Multiple versions through at least 6.x

## Timeline

- 2026-11-07: disclosed

## References

- [https://git.kernel.org/stable/c/1a9c180cd8435917b7516edfb1c9148032c28773](https://git.kernel.org/stable/c/1a9c180cd8435917b7516edfb1c9148032c28773)
- [https://git.kernel.org/stable/c/1c623e3cbf43f12dd4a72712079bfa247a9b8ba3](https://git.kernel.org/stable/c/1c623e3cbf43f12dd4a72712079bfa247a9b8ba3)

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