CVE-2026-53599

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 76% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: Elevated riskExposed: 0

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

REDAXO is a PHP-based content management system. From 5.18.2 until 5.21.1, rex_mediapool::isAllowedExtension in redaxo/src/addons/mediapool/lib/mediapool.php lets an authenticated backend user with media[upload] permission upload a JPEG/PHP polyglot named shell.php.any.jpg, which web servers with multi-extension PHP handlers can execute as the web-server user. This issue is fixed in version 5.21.1.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
50(Track*)
EG Risk 50/100SSVC: Track*

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
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
24%
KEV
Not listed

Published

July 31, 2026

Last Modified

July 31, 2026

Advisory Details (4)

Auto-updated Jul 31, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, github_pr.
github_release Patch Available

Version 5.21.1

Patch available: redaxo/core 5.21.1

https://github.com/redaxo/core/releases/tag/5.21.1
github_commit Patch Available

commit 462e36896bb6 (redaxo/core)

Patch available: redaxo/core 5.21.1 (contains commit 462e36896bb6)

https://github.com/redaxo/core/commit/462e36896bb65d292ba22d711044c23c9cfb0340
github_pr Patch Available

fix: mediapool: block dangerous extensions in any filename segment

Patch available: redaxo/core 5.21.1 (PR #6538 merged 2026-06-01)

https://github.com/redaxo/core/pull/6538
github Patch Available🟡 PoC Available

Mediapool isAllowedExtension bypass via multi-segment filename leads to authenticated RCE on Apache mod_php multi-extension handlers · Advisory · redaxo/core · GitHub

https://github.com/redaxo/core/security/advisories/GHSA-98pp-vccm-qm25

Vendor Advisories for CVE-2026-53599(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
redaxo/source5.18.2 ... 5.21.0-beta1 (8 versions)5.21.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 41× 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. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-19 19:04 UTCEG score recompute
  3. 2026-08-19 17:04 UTCEPSS rescore
  4. 2026-08-18 15:50 UTCEG score recompute
  5. 2026-08-18 13:48 UTCEPSS rescore
  6. 2026-08-18 01:00 UTCEG score recompute
  7. 2026-08-17 13:47 UTCEPSS rescore
  8. 2026-08-16 23:04 UTCEG score recompute
  9. 2026-08-16 14:56 UTCEPSS rescore
  10. 2026-08-16 10:14 UTCEG score recompute
  11. 2026-08-16 02:14 UTCEPSS rescore
  12. 2026-08-15 08:37 UTCEG score recompute
  13. 2026-08-15 01:30 UTCEPSS rescore
  14. 2026-08-14 06:58 UTCEG score recompute
  15. 2026-08-13 22:00 UTCEPSS rescore
  16. 2026-08-12 16:31 UTCEG score recompute
  17. 2026-08-12 13:51 UTCEPSS rescore
  18. 2026-08-11 14:52 UTCEG score recompute
  19. 2026-08-11 02:03 UTCEG score recompute
  20. 2026-08-11 00:00 UTCEPSS rescore
  21. 2026-08-10 00:25 UTCEG score recompute
  22. 2026-08-09 13:46 UTCEPSS rescore
  23. 2026-08-08 22:45 UTCEG score recompute
  24. 2026-08-08 16:37 UTCEPSS rescore
  25. 2026-08-07 21:06 UTCEG score recompute
Show 16 more
  1. 2026-08-06 19:28 UTCEG score recompute
  2. 2026-08-06 13:47 UTCEPSS rescore
  3. 2026-08-06 06:39 UTCEG score recompute
  4. 2026-08-05 19:17 UTCEPSS rescore
  5. 2026-08-04 16:09 UTCEG score recompute
  6. 2026-08-04 15:10 UTCEPSS rescore
  7. 2026-08-04 10:39 UTCEPSS rescore
  8. 2026-08-03 14:30 UTCEG score recompute
  9. 2026-08-03 10:36 UTCEPSS rescore
  10. 2026-08-02 12:52 UTCEG score recompute
  11. 2026-08-02 02:27 UTCEPSS rescore
  12. 2026-07-31 22:24 UTCEG score recompute
  13. 2026-07-31 22:06 UTCEG score recompute
  14. 2026-07-31 20:22 UTCEG score recompute
  15. 2026-07-31 19:48 UTCEG score recompute
  16. 2026-07-31 19:48 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-53599?
CVE-2026-53599 is a high vulnerability published on July 31, 2026. REDAXO is a PHP-based content management system. From 5.18.2 until 5.21.1, rex_mediapool::isAllowedExtension in redaxo/src/addons/mediapool/lib/mediapool.php lets an authenticated backend user with media[upload] permission upload a JPEG/PHP polyglot named shell.php.any.jpg, which web servers with…
When was CVE-2026-53599 disclosed?
CVE-2026-53599 was first published in the National Vulnerability Database on July 31, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53599 actively exploited?
CVE-2026-53599 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 75.7% of all scored CVEs.
What is the CVSS score of CVE-2026-53599?
CVE-2026-53599 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-53599?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53599, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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