{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/incusd--7.1.0/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["incusd \u003c 7.1.0"],"_cs_severities":["critical"],"_cs_tags":["path-traversal","rce","incus","s3","linux","vulnerability"],"_cs_type":"advisory","_cs_vendors":["Incus"],"content_html":"\u003cp\u003eA critical path traversal vulnerability, tracked as CVE-2026-48753, has been identified in the Incus \u003ccode\u003eincusd\u003c/code\u003e daemon affecting versions prior to 7.1.0. This flaw resides within the S3 protocol's multipart upload endpoint, specifically in the handling of the \u003ccode\u003euploadId\u003c/code\u003e parameter. Attackers can leverage this unsanitized parameter to inject path traversal sequences (e.g., \u003ccode\u003e../../\u003c/code\u003e) and write arbitrary files to sensitive locations on the host system. This arbitrary file write capability can be escalated to achieve persistent arbitrary command execution, for instance, by creating malicious cron jobs in \u003ccode\u003e/etc/cron.d\u003c/code\u003e. The successful exploitation of this vulnerability would grant an unauthenticated attacker the ability to execute commands with the privileges of the Incus service, posing a significant risk of full system compromise for affected Linux deployments utilizing Incus's S3 functionality.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker identifies a vulnerable Incus instance (version \u0026lt; 7.1.0) with an exposed S3 API, typically via \u003ccode\u003eincus config set core.storage_buckets_address\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a multipart S3 \u003ccode\u003ePUT\u003c/code\u003e request, targeting an S3 bucket configured on the vulnerable Incus instance.\u003c/li\u003e\n\u003cli\u003eThe \u003ccode\u003euploadId\u003c/code\u003e query parameter within the \u003ccode\u003ePUT\u003c/code\u003e request is maliciously manipulated, containing path traversal sequences such as \u003ccode\u003e../../../../etc/cron.d\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe request body is populated with the content of a malicious cron job entry, for example, \u003ccode\u003e* * * * * root /bin/sh -c 'id \u0026gt; /incus-s3-uploadid-bash-rce; rm -f /etc/cron.d/part-00001'\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eDue to the vulnerability in \u003ccode\u003einternal/server/storage/s3/local/multipart.go\u003c/code\u003e, Incus concatenates the unsanitized \u003ccode\u003euploadId\u003c/code\u003e directly into the target file path during the upload process.\u003c/li\u003e\n\u003cli\u003eThis results in an arbitrary file write on the host system, placing the malicious cron job content into a file like \u003ccode\u003e/etc/cron.d/part-00001\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe system's cron daemon periodically executes entries found in \u003ccode\u003e/etc/cron.d\u003c/code\u003e, triggering the newly created malicious job, leading to arbitrary command execution (e.g., \u003ccode\u003eid \u0026gt; /incus-s3-uploadid-bash-rce\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eThe executed cron job also includes a command to delete itself (\u003ccode\u003erm -f /etc/cron.d/part-00001\u003c/code\u003e), providing persistent remote code execution while attempting to remove forensic evidence.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eThe primary impact of CVE-2026-48753 is the ability for an unauthenticated attacker to achieve arbitrary file write on the host system where Incus is running. This directly enables arbitrary command execution, as demonstrated by the ability to install persistent cron jobs. Successful exploitation can lead to a complete compromise of the Incus host, allowing attackers to establish persistence, exfiltrate data, disrupt services, or pivot to other systems within the network. This vulnerability is critical due to its unauthenticated nature and the severe consequences of command execution.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003ePatch CVE-2026-48753 immediately\u003c/strong\u003e by upgrading your Incus installation to version 7.1.0 or later as advised by the advisory.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eDeploy the Sigma rule in this brief\u003c/strong\u003e to your SIEM/EDR to detect exploitation attempts of CVE-2026-48753 by monitoring for suspicious S3 PUT requests.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eMonitor web server access logs\u003c/strong\u003e for HTTP PUT requests to S3 endpoints that contain path traversal sequences (\u003ccode\u003e../../\u003c/code\u003e or \u003ccode\u003e..%2F..%2F\u003c/code\u003e) in the \u003ccode\u003euploadId\u003c/code\u003e query parameter.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEnable comprehensive file integrity monitoring\u003c/strong\u003e for critical system directories like \u003ccode\u003e/etc/cron.d\u003c/code\u003e, \u003ccode\u003e/tmp\u003c/code\u003e, and other common locations for malicious file drops.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-07-03T10:36:22Z","date_published":"2026-07-03T10:36:22Z","id":"https://feed.craftedsignal.io/briefs/2026-07-incus-s3-path-traversal-rce/","summary":"The Incus `incusd` daemon, specifically its S3 protocol multipart upload endpoint in versions prior to 7.1.0, is vulnerable to CVE-2026-48753, a critical path traversal flaw via the `uploadId` parameter, enabling unauthenticated attackers to write arbitrary files to any location on the host system, which can be leveraged for persistent arbitrary command execution.","title":"Incus S3 Multipart Upload Path Traversal Leading to RCE (CVE-2026-48753)","url":"https://feed.craftedsignal.io/briefs/2026-07-incus-s3-path-traversal-rce/"}],"language":"en","title":"CraftedSignal Threat Feed - Incusd \u003c 7.1.0","version":"https://jsonfeed.org/version/1.1"}