CVE-2021-32671

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 39.7%, top 2% 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
Elevated
10.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 40%CVSS: 10.0Exploit: NoneExposed: 0

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

Flarum is a forum software for building communities. Flarum's translation system allowed for string inputs to be converted into HTML DOM nodes when rendered. This change was made after v0.1.0-beta.16 (our last beta before v1.0.0) and was not noticed or documented. This allowed for any user to type malicious HTML markup within certain user input fields and have this execute on client browsers. The example which led to the discovery of this vulnerability was in the forum search box. Entering faux-malicious HTML markup, such as alert('test') resulted in an alert box appearing on the forum. This attack could also be modified to perform AJAX requests on behalf of a user, possibly deleting discussions, modifying their settings or profile, or even modifying settings on the Admin panel if the attack was targetted towards a privileged user. All Flarum communities that run flarum v1.0.0 or v1.0.1 are impacted. The vulnerability has been fixed and published as flarum/core v1.0.2. All communities running Flarum v1.0 have to upgrade as soon as possible to v1.0.2.

CVSS v3
10.0
EG Score
10.0(medium)
EG Risk
66(Track*)
EG Risk 66/100SSVC: 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
Severity100% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
98.5%
KEV
Not listed

Published

June 7, 2021

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Jul 18, 2026
Patch available. Sources: github, github_commit.
generic

flarum/core - Packagist.org

https://packagist.org/packages/flarum/core
github Patch Available

XSS vulnerability with translator · Advisory · flarum/framework · GitHub

https://github.com/flarum/core/security/advisories/GHSA-5qjq-69w6-fg57
github_commit

commit 440bed81b801 (flarum/core)

Fix landed in flarum/core commit 440bed81b801 — awaiting tagged release

https://github.com/flarum/core/commit/440bed81b8019dff00642c8f493b4909d505a28a

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
flarum/corev1.0.0, v1.0.11.0.2—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× 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. 2026-07-23 02:00 UTCEG score recompute
  2. 2026-07-22 22:48 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
  4. 2026-07-22 14:06 UTCEPSS rescore
  5. 2026-07-21 15:22 UTCEPSS rescore
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  7. 2026-07-20 17:05 UTCEPSS rescore
  8. 2026-07-19 14:29 UTCEPSS rescore
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  10. 2026-07-19 02:27 UTCEPSS rescore
  11. 2026-07-18 10:02 UTCEPSS rescore
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  13. 2026-07-16 17:00 UTCEPSS rescore
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  15. 2026-07-15 16:55 UTCEPSS rescore
  16. 2026-07-15 01:58 UTCEPSS rescore
  17. 2026-07-13 22:27 UTCEPSS rescore
  18. 2026-07-13 06:10 UTCEPSS rescore
  19. 2026-07-13 03:38 UTCOSV refresh
  20. 2026-07-12 05:44 UTCEPSS rescore
  21. 2026-07-12 05:44 UTCEPSS rescore
  22. 2026-07-11 08:25 UTCEPSS rescore
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  24. 2026-07-09 19:07 UTCEPSS rescore
  25. 2026-07-05 02:28 UTCEPSS rescore
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  1. 2026-07-05 02:28 UTCEPSS rescore
  2. 2026-07-01 15:04 UTCEPSS rescore
  3. 2026-06-30 23:20 UTCEPSS rescore
  4. 2026-06-30 23:20 UTCEPSS rescore
  5. 2026-06-29 14:04 UTCEPSS rescore
  6. 2026-06-28 14:05 UTCEPSS rescore
  7. 2026-06-28 04:54 UTCEPSS rescore
  8. 2026-06-28 04:54 UTCEPSS rescore
  9. 2026-06-27 03:06 UTCEPSS rescore
  10. 2026-06-25 13:48 UTCEPSS rescore
  11. 2026-06-25 13:48 UTCEPSS rescore
  12. 2026-06-24 14:03 UTCEPSS rescore
  13. 2026-06-24 14:03 UTCEPSS rescore
  14. 2026-06-24 13:32 UTCOSV refresh
  15. 2026-06-23 21:31 UTCEPSS rescore
  16. 2026-06-23 21:31 UTCEPSS rescore
  17. 2026-06-22 14:24 UTCEPSS rescore
  18. 2026-06-22 14:24 UTCEPSS rescore
  19. 2026-06-21 01:58 UTCEPSS rescore
  20. 2026-06-21 01:58 UTCEPSS rescore
  21. 2026-06-18 17:51 UTCEPSS rescore
  22. 2026-06-18 17:51 UTCEPSS rescore
  23. 2026-06-17 17:51 UTCEPSS rescore
  24. 2026-06-16 17:51 UTCEPSS rescore
  25. 2026-06-16 17:51 UTCEPSS rescore
  26. 2026-06-15 17:46 UTCEPSS rescore
  27. 2026-06-14 23:15 UTCEPSS rescore
  28. 2026-06-13 22:58 UTCEPSS rescore
  29. 2026-06-13 22:58 UTCEPSS rescore
  30. 2026-06-12 23:10 UTCEPSS rescore
  31. 2026-06-12 23:10 UTCEPSS rescore
  32. 2026-06-11 13:58 UTCEPSS rescore
  33. 2026-06-10 22:16 UTCEPSS rescore
  34. 2026-06-10 13:20 UTCEPSS rescore
  35. 2026-06-08 14:15 UTCEPSS rescore
  36. 2026-06-08 14:15 UTCEPSS rescore
  37. 2026-06-07 17:46 UTCOSV refresh
  38. 2026-06-07 15:23 UTCEPSS rescore
  39. 2026-06-07 15:23 UTCEPSS rescore
  40. 2026-06-06 13:46 UTCEPSS rescore
  41. 2026-06-06 13:46 UTCEPSS rescore
  42. 2026-06-06 13:46 UTCEPSS rescore
  43. 2026-06-05 22:45 UTCEPSS rescore
  44. 2026-06-05 06:09 UTCEPSS rescore
  45. 2026-06-05 06:09 UTCEPSS rescore
  46. 2026-06-04 13:10 UTCEPSS rescore
  47. 2026-06-04 13:10 UTCEPSS rescore
  48. 2026-06-02 20:11 UTCEPSS rescore
  49. 2026-06-02 20:11 UTCEPSS rescore
  50. 2026-06-01 13:50 UTCEPSS rescore
  51. 2026-06-01 13:50 UTCEPSS rescore
  52. 2026-05-31 22:29 UTCEPSS rescore
  53. 2026-05-31 22:29 UTCEPSS rescore
  54. 2026-05-31 00:15 UTCEPSS rescore
  55. 2026-05-31 00:15 UTCEPSS rescore
  56. 2026-05-29 13:42 UTCEPSS rescore
  57. 2026-05-29 13:42 UTCEPSS rescore
  58. 2026-05-28 13:43 UTCEPSS rescore
  59. 2026-05-28 13:43 UTCEPSS rescore
  60. 2026-05-27 13:39 UTCEPSS rescore
  61. 2026-05-27 13:39 UTCEPSS rescore
  62. 2026-05-27 13:39 UTCEPSS rescore
  63. 2026-05-26 13:42 UTCEPSS rescore
  64. 2026-05-26 07:17 UTCEPSS rescore
  65. 2026-05-26 07:17 UTCEPSS rescore
  66. 2026-05-26 07:17 UTCEPSS rescore
  67. 2026-05-23 08:12 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-32671?
CVE-2021-32671 is a critical vulnerability published on June 7, 2021. Flarum is a forum software for building communities. Flarum's translation system allowed for string inputs to be converted into HTML DOM nodes when rendered. This change was made after v0.1.0-beta.16 (our last beta before v1.0.0) and was not noticed or documented. This allowed for any user to type…
When was CVE-2021-32671 disclosed?
CVE-2021-32671 was first published in the National Vulnerability Database on June 7, 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-2021-32671 actively exploited?
CVE-2021-32671 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 98.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-32671?
CVE-2021-32671 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2021-32671?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-32671, 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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