CVE-2021-21359

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 45% 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, nvd
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 5.9Exploit: NoneExposed: 0

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

TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.

CVSS v3
5.9
EG Score
5.9(medium)
EPSS
75.2%
KEV
Not listed

Published

March 23, 2021

Last Modified

November 21, 2024

References (6)

Affected Packages

(2 across 1 ecosystem)
Packagist(2)
PackageVulnerable rangeFixed inDependents
typo3/cmsv9.0.0 ... v9.5.9 (34 versions)9.5.25—
typo3/cms-corev9.0.0 ... v9.5.9 (34 versions)9.5.25—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 47× 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. 2026-07-22 14:05 UTCEPSS rescore
  2. 2026-07-21 15:22 UTCEPSS rescore
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  4. 2026-07-20 17:04 UTCEPSS rescore
  5. 2026-07-19 14:28 UTCEPSS rescore
  6. 2026-07-19 02:26 UTCEPSS rescore
  7. 2026-07-18 23:59 UTCOSV refresh
  8. 2026-07-18 10:02 UTCEPSS rescore
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  10. 2026-07-15 16:55 UTCEPSS rescore
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  1. 2026-07-05 02:28 UTCEPSS rescore
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  3. 2026-07-04 06:29 UTCEPSS rescore
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  5. 2026-07-02 16:57 UTCEPSS rescore
  6. 2026-07-01 15:03 UTCEPSS rescore
  7. 2026-07-01 06:48 UTCOSV refresh
  8. 2026-06-30 23:20 UTCEPSS rescore
  9. 2026-06-30 23:20 UTCEPSS rescore
  10. 2026-06-29 14:04 UTCEPSS rescore
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  25. 2026-06-21 14:54 UTCEPSS rescore
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  27. 2026-06-21 01:58 UTCEPSS rescore
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  29. 2026-06-19 19:24 UTCEPSS rescore
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  31. 2026-06-18 17:51 UTCEPSS rescore
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  35. 2026-06-15 17:46 UTCEPSS rescore
  36. 2026-06-14 23:15 UTCEPSS rescore
  37. 2026-06-13 22:58 UTCEPSS rescore
  38. 2026-06-13 11:13 UTCOSV refresh
  39. 2026-06-12 23:10 UTCEPSS rescore
  40. 2026-06-12 23:10 UTCEPSS rescore
  41. 2026-06-11 13:58 UTCEPSS rescore
  42. 2026-06-10 22:16 UTCEPSS rescore
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  44. 2026-06-10 13:20 UTCEPSS rescore
  45. 2026-06-08 14:15 UTCEPSS rescore
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  47. 2026-06-07 15:23 UTCEPSS rescore
  48. 2026-06-07 15:23 UTCEPSS rescore
  49. 2026-06-06 13:46 UTCEPSS rescore
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  52. 2026-06-05 22:45 UTCEPSS rescore
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  54. 2026-06-05 06:09 UTCEPSS rescore
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  69. 2026-05-27 13:39 UTCEPSS rescore
  70. 2026-05-26 19:32 UTCEG score recompute
  71. 2026-05-26 13:42 UTCEPSS rescore
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  73. 2026-05-26 07:17 UTCEPSS rescore
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  75. 2026-05-24 16:49 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-21359?
CVE-2021-21359 is a medium vulnerability published on March 23, 2021. TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a…
When was CVE-2021-21359 disclosed?
CVE-2021-21359 was first published in the National Vulnerability Database on March 23, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-21359 actively exploited?
CVE-2021-21359 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 75.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-21359?
CVE-2021-21359 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2021-21359?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21359, 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.

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