CVE-2026-49953

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2026-06-15. the CNA's CVSS baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 3 sources updated this weekElevated
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: Elevated riskExposed: 0

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

Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical character recognition model against collected CAPTCHA samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
60(Attend)
EG Risk 60/100SSVC: Attend

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
Severity65% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
29%
KEV
Not listed

Published

June 15, 2026

Last Modified

July 28, 2026

Advisory Details (3)

Auto-updated Jun 15, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

Discuz! X5.0 CAPTCHA Bypass via Predictable Character Set | Advisories | VulnCheck

https://www.vulncheck.com/advisories/discuz-x5-0-captcha-bypass-via-predictable-character-set
generic🟡 PoC Available

Chaining Security Bugs in Discuz! X5.0: from Race Condition to Pre-Auth RCE | Karma(In)Security

https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce
generic🟡 PoC Available

Discuz! <= X5.0 OCR-based CAPTCHA Bypass Vulnerability | Karma(In)Security

https://karmainsecurity.com/KIS-2026-10

Vendor Advisories for CVE-2026-49953(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 15× in last 7d / 74× 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.

Showing the most recent 100 of 161 total refreshes for this CVE.

  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-24 23:34 UTCEG score recompute
  3. 2026-08-24 23:34 UTCGHSA enrichment
  4. 2026-08-23 09:45 UTCEG score recompute
  5. 2026-08-23 09:45 UTCGHSA enrichment
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-21 11:57 UTCEG score recompute
  9. 2026-08-21 11:57 UTCGHSA enrichment
  10. 2026-08-20 22:55 UTCEPSS rescore
  11. 2026-08-20 12:30 UTCEG score recompute
  12. 2026-08-20 12:30 UTCGHSA enrichment
  13. 2026-08-19 17:04 UTCEPSS rescore
  14. 2026-08-19 13:14 UTCEG score recompute
  15. 2026-08-19 13:14 UTCGHSA enrichment
  16. 2026-08-18 13:48 UTCEPSS rescore
  17. 2026-08-17 13:47 UTCEPSS rescore
  18. 2026-08-17 02:59 UTCEG score recompute
  19. 2026-08-17 02:59 UTCGHSA enrichment
  20. 2026-08-16 14:56 UTCEPSS rescore
  21. 2026-08-16 04:25 UTCEG score recompute
  22. 2026-08-16 04:25 UTCGHSA enrichment
  23. 2026-08-16 02:14 UTCEPSS rescore
  24. 2026-08-15 05:51 UTCEG score recompute
  25. 2026-08-15 05:51 UTCGHSA enrichment
Show 75 more
  1. 2026-08-15 01:30 UTCEPSS rescore
  2. 2026-08-14 06:47 UTCEG score recompute
  3. 2026-08-14 06:47 UTCGHSA enrichment
  4. 2026-08-13 22:00 UTCEPSS rescore
  5. 2026-08-13 08:14 UTCEG score recompute
  6. 2026-08-13 08:14 UTCGHSA enrichment
  7. 2026-08-12 13:51 UTCEPSS rescore
  8. 2026-08-12 09:40 UTCEG score recompute
  9. 2026-08-12 09:40 UTCGHSA enrichment
  10. 2026-08-11 11:06 UTCEG score recompute
  11. 2026-08-11 11:06 UTCGHSA enrichment
  12. 2026-08-11 00:00 UTCEPSS rescore
  13. 2026-08-10 12:32 UTCGHSA enrichment
  14. 2026-08-09 13:57 UTCEG score recompute
  15. 2026-08-09 13:57 UTCGHSA enrichment
  16. 2026-08-09 13:46 UTCEPSS rescore
  17. 2026-08-08 16:37 UTCEPSS rescore
  18. 2026-08-08 15:24 UTCGHSA enrichment
  19. 2026-08-07 16:49 UTCEG score recompute
  20. 2026-08-07 16:49 UTCGHSA enrichment
  21. 2026-08-06 18:15 UTCEG score recompute
  22. 2026-08-06 18:15 UTCGHSA enrichment
  23. 2026-08-06 13:47 UTCEPSS rescore
  24. 2026-08-05 19:41 UTCEG score recompute
  25. 2026-08-05 19:41 UTCGHSA enrichment
  26. 2026-08-05 19:17 UTCEPSS rescore
  27. 2026-08-04 15:42 UTCEG score recompute
  28. 2026-08-04 15:42 UTCGHSA enrichment
  29. 2026-08-04 15:10 UTCEPSS rescore
  30. 2026-08-04 10:39 UTCEPSS rescore
  31. 2026-08-03 10:36 UTCEPSS rescore
  32. 2026-08-03 08:58 UTCGHSA enrichment
  33. 2026-08-02 07:25 UTCEG score recompute
  34. 2026-08-02 07:25 UTCGHSA enrichment
  35. 2026-08-02 02:27 UTCEPSS rescore
  36. 2026-08-01 08:51 UTCEG score recompute
  37. 2026-08-01 08:51 UTCGHSA enrichment
  38. 2026-08-01 04:16 UTCEPSS rescore
  39. 2026-07-31 04:31 UTCEG score recompute
  40. 2026-07-31 04:31 UTCGHSA enrichment
  41. 2026-07-30 16:28 UTCEPSS rescore
  42. 2026-07-30 05:11 UTCEG score recompute
  43. 2026-07-30 05:11 UTCGHSA enrichment
  44. 2026-07-30 01:30 UTCEPSS rescore
  45. 2026-07-29 03:24 UTCEG score recompute
  46. 2026-07-29 03:24 UTCGHSA enrichment
  47. 2026-07-28 15:37 UTCEPSS rescore
  48. 2026-07-28 01:53 UTCEG score recompute
  49. 2026-07-28 01:53 UTCGHSA enrichment
  50. 2026-07-26 20:13 UTCEG score recompute
  51. 2026-07-26 20:13 UTCGHSA enrichment
  52. 2026-07-26 14:54 UTCEPSS rescore
  53. 2026-07-25 14:18 UTCEPSS rescore
  54. 2026-07-24 14:18 UTCEPSS rescore
  55. 2026-07-23 14:18 UTCEPSS rescore
  56. 2026-07-23 03:18 UTCEG score recompute
  57. 2026-07-22 14:08 UTCEPSS rescore
  58. 2026-07-21 15:25 UTCEPSS rescore
  59. 2026-07-20 17:08 UTCEPSS rescore
  60. 2026-07-19 14:31 UTCEPSS rescore
  61. 2026-07-19 14:31 UTCEPSS rescore
  62. 2026-07-19 02:29 UTCEPSS rescore
  63. 2026-07-18 10:04 UTCEPSS rescore
  64. 2026-07-16 17:03 UTCEPSS rescore
  65. 2026-07-16 14:40 UTCGHSA enrichment
  66. 2026-07-15 16:57 UTCEPSS rescore
  67. 2026-07-15 16:57 UTCEPSS rescore
  68. 2026-07-15 15:47 UTCGHSA enrichment
  69. 2026-07-15 02:00 UTCEPSS rescore
  70. 2026-07-14 14:21 UTCGHSA enrichment
  71. 2026-07-13 22:30 UTCEPSS rescore
  72. 2026-07-13 15:45 UTCGHSA enrichment
  73. 2026-07-13 06:13 UTCEPSS rescore
  74. 2026-07-12 17:08 UTCGHSA enrichment
  75. 2026-07-12 05:46 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-49953?
CVE-2026-49953 is a medium vulnerability published on June 15, 2026. Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical…
When was CVE-2026-49953 disclosed?
CVE-2026-49953 was first published in the National Vulnerability Database on June 15, 2026, with the most recent update on July 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49953 actively exploited?
CVE-2026-49953 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 71.4% of all scored CVEs.
What is the CVSS score of CVE-2026-49953?
CVE-2026-49953 has a CVSS v4.0 base score of 6.5 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-49953?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-49953, 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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