CVE-2026-35527: Incus is an open source container and virtual machine manager. In versions prior to 7.0.0, the image import flow issues an outbound HEAD request to a ...

Description

Incus is an open source container and virtual machine manager. In versions prior to 7.0.0, the image import flow issues an outbound HEAD request to a user-supplied URL before validating the request against project restrictions such as restricted.images.servers. The imgPostURLInfo function constructs and sends a HEAD request directly from the attacker-supplied source URL to resolve image metadata, and this network interaction occurs before the flow reaches the point where the import would be rejected by policy. Although the actual image download is blocked by the project restriction, an authenticated user can coerce the daemon into making blind HEAD requests to arbitrary destinations. These requests include server metadata in custom headers (Incus-Server-Architectures, Incus-Server-Version), which discloses information about the host environment to the attacker-controlled endpoint. This blind SSRF primitive can be used to probe internal services, unroutable address space, or cloud metadata endpoints reachable from the host. This vulnerability pattern is similar to CVE-2026-24767. This issue has been fixed in version 7.0.0.

Metrics

CVSS 3.1

5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N

CVSS 4.0

5.3/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.27%

18.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-918

Affected Software

Vendor	Product	Versions
Linuxcontainers	Incus	< 7.0.0

References

https://github.com/lxc/incus/blob/v6.22.0/cmd/incusd/images.goProduct
https://github.com/lxc/incus/security/advisories/GHSA-8gw4-p4wq-4hcvExploit, Vendor Advisory
https://github.com/lxc/incus/security/advisories/GHSA-8gw4-p4wq-4hcvExploit, Vendor Advisory

Timeline

Published: May 5, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-35527?

Incus is an open source container and virtual machine manager. In versions prior to 7.0.0, the image import flow issues an outbound HEAD request to a user-supplied URL before validating the request against project restrictions such as restricted.images.servers. The imgPostURLInfo function constructs and sends a HEAD request directly from the attacker-supplied source URL to resolve image metadata, and this network interaction occurs before the flow reaches the point where the import would be rejected by policy. Although the actual image download is blocked by the project restriction, an authenticated user can coerce the daemon into making blind HEAD requests to arbitrary destinations. These requests include server metadata in custom headers (Incus-Server-Architectures, Incus-Server-Version), which discloses information about the host environment to the attacker-controlled endpoint. This blind SSRF primitive can be used to probe internal services, unroutable address space, or cloud metadata endpoints reachable from the host. This vulnerability pattern is similar to CVE-2026-24767. This issue has been fixed in version 7.0.0.

How severe is CVE-2026-35527?

CVE-2026-35527 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2026-35527?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.