Lychee: Path traversal in secure image links allows authenticated file read
Summary
Lychee, a free open-source photo-management tool, contains a path traversal flaw in SecurePathController, which serves requests on GET /image/{path}. The prefix check runs before dot segments are canonicalized, so encoded traversal segments can pass it. Only the non-default configuration with temporary image links enabled and related settings in the stated state is affected, and the attacker needs a valid user account. A successful attacker can read files available to the web process, including application configuration and other users' private images; disclosed APP_KEY or database credentials could enable further compromise.
Affected
- Lychee versions before 7.6.4
- Only with temporary_image_link_enabled enabled, temporary_image_link_when_logged_in disabled and secure_image_link_enabled disabled (non-default)
- Earliest affected version: Unknown.
Fixed in
- Upgrade to Lychee 7.6.4 or later (fix commit f4553f6e0145ec4e02360c6121bd169e87b5d05f).
Workaround
- No vendor-documented workaround.
- Disabling temporary image links is likely to remove the exposure, but this is not verified by the vendor.
Exploitation
- CISA SSVC: Exploitation none, Automatable no, Technical Impact partial.
- No known exploitation or public proof of concept found in the sources checked. This is not confirmed absence.
Our recommendation
- Identify all Lychee instances and their versions.
- Upgrade to 7.6.4 at minimum, preferably to the latest release.
- Check whether temporary image links are enabled and whether they are needed; disable them if not.
- Review web server and application logs for unusual /image/ requests.
- Rotate APP_KEY and database credentials if exposure is suspected.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-j5ff-34x8-xxqg github.com
- Fix commit f4553f6e0145ec4e02360c6121bd169e87b5d05f github.com
- Pull request #4465 github.com
- Lychee release v7.6.4 github.com
- OSV CVE-2026-62679 osv.dev
- VulDB 420726 vuldb.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 08:31.
Original description (NVD)
Lychee is a free, open-source photo-management tool. Prior to 7.6.4, SecurePathController, which serves GET /image/{path}, concatenates the attacker-controlled path with the local storage root and performs a string-prefix check before canonicalizing dot segments. Under the supported non-default configuration with temporary_image_link_enabled enabled, temporary_image_link_when_logged_in disabled, and secure_image_link_enabled disabled, any authenticated user can submit encoded traversal segments that pass the prefix check and are later resolved by filesystem operations. This permits reading files available to the web process, including application configuration and other users' private images, and disclosed APP_KEY or database credentials can enable further compromise. This issue is fixed in version 7.6.4.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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