CVE-2026-100523

MEDIUMPre-NVD 6.16.1—
EchelonGraph scoreHIGH confidence

Score 6.1 from GitHub Security Advisory published 2026-09-26. A secondary CVSS source baseline 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.1Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

Cotonti through 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes the redirect parameter without domain validation. Unauthenticated attackers can craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing attacks.

CVSS v3
6.1
EG Score
6.1MEDIUMhigh confidence
EG Risk
32
EG Risk 32/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity61% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
7th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 26, 2026

Last Modified

September 26, 2026

Advisory Details (6)

Auto-updated Sep 26, 2026
No patch confirmed yet. Sources: github_pr.
generic

Cotonti through 1.0.0 Open Redirect via message.php redirect parameter | Advisories | VulnCheck

https://www.vulncheck.com/advisories/cotonti-through-1.0.0-open-redirect-via-message-php-redirect-parameter
github_pr

Security hardening (batch 1): CSRF tokens, XSS escaping, redirect validation, CSPRNG tokens, upload & object-injection fixes

Upstream fix in progress (PR #1908 · Cotonti/Cotonti, state=open)

https://github.com/Cotonti/Cotonti/pull/1908
generic

Security: ~60 confirmed vulnerabilities in current master (f43f1fc) — CSRF, XSS, open redirect, weak tokens, upload/RCE chains (coordinated disclosure via VulnCheck CNA) · Issue #1907 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/issues/1907
generic

Cotonti/system/common.php at 1.0.0 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/blob/1.0.0/system/common.php
generic

Cotonti/message.php at 1.0.0 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/blob/1.0.0/message.php
generic

GitHub - Cotonti/Cotonti: Fast, reliable and flexible PHP CMF/CMS · GitHub

https://github.com/Cotonti/Cotonti

Vendor Advisories for CVE-2026-100523(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 19× in last 7d / 25× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-04 05:35 UTCEG score recompute
  2. 2026-10-04 05:35 UTCGHSA enrichment
  3. 2026-10-03 14:25 UTCEPSS rescore
  4. 2026-10-03 05:04 UTCEG score recompute
  5. 2026-10-03 05:04 UTCGHSA enrichment
  6. 2026-10-02 04:33 UTCEG score recompute
  7. 2026-10-02 04:33 UTCGHSA enrichment
  8. 2026-10-01 19:49 UTCEPSS rescore
  9. 2026-10-01 04:01 UTCEG score recompute
  10. 2026-10-01 04:00 UTCGHSA enrichment
  11. 2026-09-30 15:02 UTCEPSS rescore
  12. 2026-09-30 03:29 UTCEG score recompute
  13. 2026-09-30 03:29 UTCGHSA enrichment
  14. 2026-09-29 15:20 UTCEPSS rescore
  15. 2026-09-29 02:57 UTCEG score recompute
  16. 2026-09-29 02:57 UTCGHSA enrichment
  17. 2026-09-28 13:50 UTCEPSS rescore
  18. 2026-09-28 02:25 UTCEG score recompute
  19. 2026-09-28 02:25 UTCGHSA enrichment
  20. 2026-09-27 01:54 UTCEG score recompute
  21. 2026-09-27 01:54 UTCGHSA enrichment
  22. 2026-09-26 15:58 UTCEPSS rescore
  23. 2026-09-26 01:20 UTCEG score recompute
  24. 2026-09-26 01:12 UTCEG score recompute
  25. 2026-09-26 01:09 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-100523?
CVE-2026-100523 is a medium vulnerability published on September 26, 2026. Cotonti through 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes the redirect parameter without domain validation. Unauthenticated attackers can craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing…
When was CVE-2026-100523 disclosed?
CVE-2026-100523 was first published on September 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100523 actively exploited?
CVE-2026-100523 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100523?
CVE-2026-100523 has a CVSS base score of 6.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-100523?
No fix for CVE-2026-100523 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-100523 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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