# CVE-2026-99177: Linux kernel KVM SEV race condition in sev_gmem_post_populate()

Source: https://junglewise.ai/threats/cve-2026-99177-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-99177 · Severity: info · Published 2026-10-28

The Linux kernel's KVM (virtualization layer) has a race condition in SEV (Secure Encrypted Virtualization) guest memory initialization. An incorrect page-marking function could allow a page's mapping to be freed concurrently, potentially causing memory corruption or system instability in virtualized environments.

Technologies: [Linux kernel](https://junglewise.ai/threats/technologies/x-linux-kernel).

## Quick answers

**Is CVE-2026-99177 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99177 being exploited in the wild.

**How severe is CVE-2026-99177?** Informational severity, published 28 October 2026.

**Which products and versions are affected?** Linux kernel versions with commit 97cd21d57e9b and later, prior to fix.

**Is there a fix for CVE-2026-99177?** A patch was published on 2026-09-30. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-99177 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-99177?** 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 vulnerability is a missing lock in the sev_gmem_post_populate() function in arch/x86/kvm/svm/sev.c. The code calls set_page_dirty() on a page obtained from get_user_pages_fast() without holding required locks, violating the API contract that the page mapping must remain stable. The fix replaces set_page_dirty() with set_page_dirty_lock() to properly serialize access and prevent concurrent mapping removal.

## Affected products

- Linux kernel versions with commit 97cd21d57e9b and later, prior to fix

## Timeline

- 2026-10-28: disclosed
- 2026-09-30: patched

## References

- [https://git.kernel.org/stable/c/184382f9852d433af21de96c334ecf43b8414ed8](https://git.kernel.org/stable/c/184382f9852d433af21de96c334ecf43b8414ed8)
- [https://git.kernel.org/stable/c/97818b2fa7082e940ddd36dab12a68615300e798](https://git.kernel.org/stable/c/97818b2fa7082e940ddd36dab12a68615300e798)

## Related threats

- [Linux kernel mmap bounds check vulnerability in mman.c](https://junglewise.ai/threats/cve-2026-58813-in-mmap-of-mman-c-there-is-a-possible-way-to-trigger-an-out-of)
- [Linux kernel TIPC double fetch information disclosure](https://junglewise.ai/threats/cve-2026-0193-in-handle-rx-msg-of-tipc-virtio-dev-there-is-a-possible-double)
- [Linux kernel xen-netback use-after-free in mcast_addr_list_free](https://junglewise.ai/threats/cve-2026-100081-in-the-linux-kernel-the-following-vulnerability-has-been)
- [Linux kernel io_uring denial of service via preemption window](https://junglewise.ai/threats/cve-2026-99252-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel printk kthread boot hang in SMP systems](https://junglewise.ai/threats/cve-2026-99250-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)