Auth bypass in Opensource-Socialnetwork
CVE-2026-108164
Open Source Social Network (OSSN) through 10.1 contains an insecure direct object reference vulnerability in components/OssnMessages/ossn_com.php that allows authenticated users to read other users' private message attachments. Attackers can request the /messages/attachment/{guid} route with sequential or guessed file GUIDs to retrieve attachments from private conversations without sender or recipient verification.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/opensource-socialnetwork/opensource-socialnetwork/issues/2641 (issue-tracking)
- github.com/opensource-socialnetwork/opensource-socialnetwork/commit/2e9733d8eaa… (patch)
- hackmd.io/@leediay/ossn-idor-message-attachment (technical-description, exploit)
- github.com/opensource-socialnetwork/opensource-socialnetwork/blob/48b53f5b95488… (technical-description)
- github.com/opensource-socialnetwork/opensource-socialnetwork (product)
- www.vulncheck.com/advisories/open-source-social-network-ossn-through-10.1-idor-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-108164?
- CVE-2026-108164 is a medium-severity vulnerability in Opensource-Socialnetwork, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-10-10.
- How severe is CVE-2026-108164?
- Medium severity. CVSS v3 base score is 6.5 out of 10.