# CVE-2026-99287: Linux kernel xen-netback double unmap memory corruption

Source: https://junglewise.ai/threats/cve-2026-99287-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-99287 · Severity: info · Published 2026-11-10

The Linux kernel's Xen virtual network backend driver (xen-netback) contains a flaw in how it cleans up ring pointers when network ring mapping fails. If a second cleanup attempt occurs, the driver tries to unmap already-freed memory, which could lead to memory corruption or system instability on virtual machines using Xen networking.

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

## Quick answers

**Is CVE-2026-99287 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99287 being exploited in the wild.

**How severe is CVE-2026-99287?** Informational severity, published 10 November 2026.

**Which products and versions are affected?** Linux Kernel multiple versions through 7.3.y.

**Is there a fix for CVE-2026-99287?** A patch was published on 2026-11-10: committed upstream as f96f16592a32430a0582309d73a873b6d3ee2bdb Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-99287 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-99287?** 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

A double-free condition exists in xenvif_unmap_frontend_data_rings() where ring pointers are not zeroed after unmapping. If xenvif_map_frontend_data_rings() fails during a retry when rings are already mapped, the cleanup path calls unmap a second time on stale pointers. The fix zeros the ring pointers (tx.sring and rx.sring) after calling xenbus_unmap_ring_vfree(), preventing the double-unmap. This affects the kernel's Xen networking backend driver in the net/xen-netback subsystem.

## Affected products

- Linux kernel multiple versions through 7.3.y

## Timeline

- 2026-11-10: disclosed
- 2026-11-10: patched: committed upstream as f96f16592a32430a0582309d73a873b6d3ee2bdb

## References

- [https://git.kernel.org/stable/c/87fd475dc4e354088f6534285388e7b061f54b35](https://git.kernel.org/stable/c/87fd475dc4e354088f6534285388e7b061f54b35)
- [https://git.kernel.org/stable/c/c5f54af611ff6fe1d53fa05d8e87b469dc56122b](https://git.kernel.org/stable/c/c5f54af611ff6fe1d53fa05d8e87b469dc56122b)

## Related threats

- [Linux kernel PMC uninitialized clock rate in 32-bit Tegra](https://junglewise.ai/threats/cve-2026-99259-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel x86 Hyper-V memory access violation](https://junglewise.ai/threats/cve-2026-99258-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel io_uring signal loss in worker exit](https://junglewise.ai/threats/cve-2026-99228-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel mv643xx_eth NULL pointer dereference in PHY probe](https://junglewise.ai/threats/cve-2026-99197-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel unicode map use-after-free in path lookup](https://junglewise.ai/threats/cve-2026-99180-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)