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

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-10 · updated 2026-10-16
Weakness: CWE-639

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

opensource-socialnetwork: through 10.1

References

https://github.com/opensource-socialnetwork/opensource-socialnetwork
https://github.com/opensource-socialnetwork/opensource-socialnetwork/blob/48b53f5b95488187715b2d5b5ae46a993267f83d/components/OssnMessages/ossn_com.php#L149-L156
https://github.com/opensource-socialnetwork/opensource-socialnetwork/commit/2e9733d8eaafccdaef3d9b498348c8332e51f48b
https://github.com/opensource-socialnetwork/opensource-socialnetwork/issues/2641
https://hackmd.io/@leediay/ossn-idor-message-attachment
https://www.vulncheck.com/advisories/open-source-social-network-ossn-through-10.1-idor-via-message-attachment-route

Get alerted when CVE-2026-108164 or the next vulnerability affects your stack