---
id: "CVE-2026-115374"
kind: "vulnerability"
aliases: ["CVE-2026-115374"]
title: "Incus: S3 server lets presigned URL holders copy other bucket objects"
severity: "high"
cvss: 7.1
epss: 0.00153
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["incus", "infrastructure", "object-storage", "s3", "self-hosted"]
not_affected_if: ["default-config", "no-s3-server"]
published_at: "2026-10-22T19:17:43+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T03:31:27+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115374", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115374", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# Incus: S3 server lets presigned URL holders copy other bucket objects

Incus's built-in S3 server does not verify some x-amz-* headers in presigned URLs, so a holder of a presigned upload URL can add an unsigned X-Amz-Copy-Source header. This copies other objects in the bucket onto the granted key, exposing their contents and ETags.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `incus version` and compare against the affected ranges: 7.0.0 before 7.0.2 and 7.1.0 before 7.5.0.
- Check whether the built-in S3 server is enabled in the Incus configuration (unknown how to confirm from the sources).

## Fix

- Upgrade Incus to `7.0.2` on the 7.0 branch or to `7.5.0` on the 7.1 branch.

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115374
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115374

## From the sources

Incus 7.0.0 before 7.0.2 and 7.1.0 before 7.5.0 contains a signature verification flaw in its built-in S3 server that allows presigned URL holders to inject unsigned x-amz-* headers. Attackers can add an unsigned X-Amz-Copy-Source header to a presigned upload URL to copy other bucket objects onto the granted key, disclosing their contents and ETags.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_