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.
CVE-2026-108164
“—” beside the score: it is equal to the CVSS score beside it.
Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-10-10. A secondary CVSS source baseline 6.5; sources differ by 0.0.
Also known asEUVD-2026-96319 (ENISA EUVD) · GHSA-6qx6-fpjx-pg68 (GitHub Security Advisories)Source: ENISA EUVD
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5MEDIUMhigh confidence
- EG Risk
- 45EG Risk 45/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity65% × 45%Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule, then apply it. - EPSS PROB
- 0.3%
- EPSS %ILE
- 17th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule, then apply it.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 10, 2026
Last Modified
October 16, 2026
Advisory Details (6)
Auto-updated Oct 10, 2026Open Source Social Network (OSSN) through 10.1 IDOR via Message Attachment Route | Advisories | VulnCheck
https://www.vulncheck.com/advisories/open-source-social-network-ossn-through-10.1-idor-via-message-attachment-routeGitHub - opensource-socialnetwork/opensource-socialnetwork: Open Source Social Network (OSSN) is a powerful open-source social networking software developed in PHP. It enables you to create a fully functional social networking website that fosters community engagement and helps your members form meaningful social relationships. · GitHub
https://github.com/opensource-socialnetwork/opensource-socialnetworkopensource-socialnetwork/components/OssnMessages/ossn_com.php at 48b53f5b95488187715b2d5b5ae46a993267f83d · opensource-socialnetwork/opensource-socialnetwork · GitHub
https://github.com/opensource-socialnetwork/opensource-socialnetwork/blob/48b53f5b95488187715b2d5b5ae46a993267f83d/components/OssnMessages/ossn_com.php#L149-L156OSSN IDOR - Unauthorized Access to Message Attachments - HackMD
https://hackmd.io/@leediay/ossn-idor-message-attachmentcommit 2e9733d8eaaf (opensource-socialnetwork/opensource-socialnetwork)
Fix landed in opensource-socialnetwork/opensource-socialnetwork commit 2e9733d8eaaf — awaiting tagged release
https://github.com/opensource-socialnetwork/opensource-socialnetwork/commit/2e9733d8eaafccdaef3d9b498348c8332e51f48b[B] Check file download in messages ownership checking · Issue #2641 · opensource-socialnetwork/opensource-socialnetwork · GitHub
https://github.com/opensource-socialnetwork/opensource-socialnetwork/issues/2641Vendor Advisories for CVE-2026-108164(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 43× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-29 14:57 UTCEG score recompute
- 2026-10-29 14:57 UTCGHSA enrichmentGHSA-6qx6-fpjx-pg68 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
- 2026-10-25 14:54 UTCEG score recompute
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-23 08:30 UTCEG score recompute
- 2026-10-23 08:29 UTCGHSA enrichmentGHSA-6qx6-fpjx-pg68 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-18 05:07 UTCEG score recompute
- 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-16 19:44 UTCEG score recompute
- 2026-10-16 19:44 UTCGHSA enrichmentGHSA-6qx6-fpjx-pg68 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 16th percentile
Show 18 moreShow fewer
- 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-13 19:51 UTCEG score recompute
- 2026-10-13 19:50 UTCGHSA enrichmentGHSA-6qx6-fpjx-pg68 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-13 18:39 UTCEG score recompute
- 2026-10-13 18:38 UTCGHSA enrichmentGHSA-6qx6-fpjx-pg68 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-12 16:38 UTCEG score recompute
- 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-11 20:14 UTCEG score recompute
- 2026-10-11 18:26 UTCEG score recompute
- 2026-10-11 14:59 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 16th percentile
- 2026-10-11 13:03 UTCEG score recompute
- 2026-10-11 13:02 UTCGHSA enrichmentGHSA-6qx6-fpjx-pg68 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-10 14:25 UTCEG score recompute
- 2026-10-10 14:00 UTCEG score recomputeFirst assessed: 6.5 MEDIUM
- 2026-10-10 14:00 UTCMITRE cvelistV5first tracked
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Frequently asked(5)
What is CVE-2026-108164?
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What is the CVSS score of CVE-2026-108164?
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Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-108164
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