CVE-2026-57965: Red Hat spice-vdagent integer overflow in udscs_write

CVE-2026-57965 · Severity: medium · CVSS 5.1 · Published 2026-06-29

A vulnerability exists in the SPICE agent, a tool used to improve the user experience in virtual machines by enabling features like clipboard sharing and file transfers. A compromised or malicious host server can send a specially crafted message to the virtual machine, causing the agent to crash. This results in a denial of service for the virtual machine's integration features, though it typically requires the host server to already be compromised.

Technologies: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9. Vendors: Red Hat.

Quick answers

Is CVE-2026-57965 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-57965 being exploited in the wild.
How severe is CVE-2026-57965?
Medium severity, with a CVSS score of 5.1, published 29 June 2026.
Which products and versions are affected?
Red Hat Enterprise Linux 10 affected status; Red Hat Enterprise Linux 6 affected status; Red Hat Enterprise Linux 7 affected status; Red Hat Enterprise Linux 8 affected status; and 1 more.
Is there a fix for CVE-2026-57965?
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-2026-57965 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-57965?
Check whether you run Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 or one of the others listed 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

An integer overflow vulnerability exists in the udscs_write() function within src/udscs.c of spice-vdagent. The function calculates a buffer size using 32-bit unsigned integers (guint) without proper bounds checking; specifically, when a large 'size' value is provided in a VDAgentMessage (such as clipboard or file transfers), the calculation wraps around to a small value. This leads to a heap buffer overflow during a subsequent memcpy operation. While the attack vector is local to the guest, it is triggered by the SPICE host. Exploitation results in a SIGBUS crash of the spice-vdagent daemon, causing a Denial of Service (DoS) for guest-host integration features. The vulnerability is confirmed via AddressSanitizer.

Affected products

  • Red Hat Red Hat Enterprise Linux 6 affected status
  • Red Hat Red Hat Enterprise Linux 7 affected status
  • Red Hat Red Hat Enterprise Linux 8 affected status
  • Red Hat Red Hat Enterprise Linux 9 affected status
  • Red Hat Red Hat Enterprise Linux 10 affected status
  • SPICE Project spice-vdagent

Timeline

  • 2026-06-26: disclosed: Initial report in Red Hat Bugzilla
  • 2026-06-29: advisory: CVE published to NVD dataset

References

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