Vulnerability · Published Oct 10, 2026 · Assigned by VulnCheck

CVE-2026-108164Open Source Social Network (OSSN) through 10.1 IDOR via Message Attachment Route

Medium 6.5

In plain English

A medium-severity authorization bypass via user-controlled key in opensource-socialnetwork from opensource-socialnetwork. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.3%top 82.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
opensource-socialnetwork	opensource-socialnetwork	0 – through 10.1

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

References

https://github.com/opensource-socialnetwork/opensource-socialnetwork/issues/2641 issue-tracking
https://github.com/opensource-socialnetwork/opensource-socialnetwork/commit/2e9733d8eaafccdaef3d9b498348c8332e51f48b patch
https://hackmd.io/@leediay/ossn-idor-message-attachment exploit, technical-description
https://github.com/opensource-socialnetwork/opensource-socialnetwork/blob/48b53f5b95488187715b2d5b5ae46a993267f83d/components/OssnMessages/ossn_com.php#L149-L156 technical-description
https://github.com/opensource-socialnetwork/opensource-socialnetwork product
VulnCheck Advisory: Open Source Social Network (OSSN) through 10.1 IDOR via Message Attachment Route third-party-advisory