CVE-2026-105958
Description
A flaw was found in spice-server. Multiple migration data handlers use client-supplied offsets from SPICE_MSGC_MIGRATE_DATA messages without bounds validation, allowing a malicious authenticated SPICE client during VM live migration to read arbitrary heap memory or trigger heap corruption via out-of-bounds read and write operations on the message buffer.
Statement
Red Hat has evaluated this vulnerability as an Important severity flaw because an authenticated attacker could corrupt host memory and compromise the hypervisor process running SPICE, breaking virtualization boundaries. To trigger this condition, a remote user must possess valid credentials to connect to the SPICE remote desktop service while a virtual machine is actively undergoing live migration. In typical enterprise deployments where SPICE interfaces are restricted to isolated management networks, exposure is limited by network topology and the narrow timing window required for the attack.
Mitigation
This vulnerability is only exploitable during VM live migration by an authenticated SPICE client. If live migration is not required, disabling it eliminates the attack surface. If live migration is needed, restrict SPICE client connections to trusted networks using firewall rules and enforce strong authentication (TLS with mutual certificate validation, or SASL with strong credentials) to limit who can connect as a SPICE client.
--- CME Mitigation Guidance (2026-10-20) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to enforce strict bounds validation on client-supplied offsets and buffer lengths across all SPICE migration data handlers prior to memory operations: upgrade to the fixed Spice/Spice Server builds, which validate migration data offsets and read bounds against declared message lengths instead of reallocating from attacker-controlled values, closing all 4 injection vectors (RedCharDevice restore via write_data_ptr offset manipulation, smartcard restore via read_data_ptr offset manipulation, reds agent state restore via msg_header_ptr offset manipulation, DisplayChannelClient migrate data handling via surfaces_at_client_ptr offset manipulation). Until patched, this is a concern on Linux hosts running Spice Server with VM live migration enabled, so disable VM live migration if not required, restrict SPICE client network access using firewall rules, and enforce strong authentication via SASL or mutual TLS. As a compensating measure, randomize heap and binary addresses using ASLR to impede reliable exploitation of out-of-bounds reads and writes, enforce full RELRO and PIE to make Global Offset Table entries read-only and prevent control flow diversion via heap corruption, validate indirect call targets using Control Flow Integrity or shadow call stacks to block redirection upon corruption of function pointers or vtables, enable FORTIFY_SOURCE to detect buffer overflows during memory copy operations such as memcpy and abort execution, and confine the SPICE server process using SELinux in enforcing mode to restrict host access if arbitrary code execution occurs. These controls limit blast radius and contain exploitation, but they do not fix the underlying unchecked migration data offsets defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-301 SELinux (Enforcing Mode) (medium)
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Acknowledgements
Upstream acknowledges Tristan Madani (Talence Security) as the original reporter.
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