CVE-2026-49854

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 73% 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
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
EPSS PROB
0.4%
EPSS %ILE
34th
KEV
Not listed

Published

June 12, 2026

Last Modified

July 15, 2026

Advisory Details (3)

Auto-updated Jul 15, 2026
Patch available. Sources: github_commit, github_pr, github.
githubMentions a patch (unverified)

Out-of-bounds memory access in C extension · Advisory · tornadoweb/tornado · GitHub

https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9
github_pr

Combined changes for release 6.5.6

Fix merged in tornadoweb/tornado PR #3626 on 2026-05-27 — awaiting tagged release

https://github.com/tornadoweb/tornado/pull/3626
github_commit

commit 96dc88c2a057 (tornadoweb/tornado)

Fix landed in tornadoweb/tornado commit 96dc88c2a057 — awaiting tagged release

https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac

Vendor Advisories for CVE-2026-49854(1)

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

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
python-tornado6.1.0-1 ... 6.5.5-4 (28 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
python-tornado6.2.0-3 ... 6.5.5-5 (24 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
python-tornado6.4.2-3 ... 6.5.5-5 (13 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
python-tornado6.4.2-3 ... 6.5.5-5 (11 versions)
  • every version on: no fix on record
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
tornado0.2 ... 6.5b1 (81 versions)
  • every version up to 6.5.6: fixed in 6.5.6
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 22× 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 106 total refreshes for this CVE.

  1. 2026-10-09 20:07 UTCEPSS rescore
  2. 2026-10-08 17:12 UTCEPSS rescore
  3. 2026-10-07 23:48 UTCEPSS rescore
  4. 2026-10-06 15:18 UTCEPSS rescore
  5. 2026-10-05 17:43 UTCEPSS rescore
  6. 2026-10-04 23:22 UTCEPSS rescore
  7. 2026-10-03 14:25 UTCEPSS rescore
  8. 2026-10-03 08:39 UTCOSV refresh
  9. 2026-10-01 19:50 UTCEPSS rescore
  10. 2026-09-30 15:03 UTCEPSS rescore
  11. 2026-09-28 13:51 UTCEPSS rescore
  12. 2026-09-27 13:48 UTCEPSS rescore
  13. 2026-09-26 15:59 UTCEPSS rescore
  14. 2026-09-26 00:27 UTCEPSS rescore
  15. 2026-09-23 17:53 UTCEPSS rescore
  16. 2026-09-20 20:16 UTCEPSS rescore
  17. 2026-09-18 19:28 UTCEPSS rescore
  18. 2026-09-16 14:08 UTCEPSS rescore
  19. 2026-09-16 05:15 UTCEPSS rescore
  20. 2026-09-14 03:58 UTCEG score recompute
  21. 2026-09-13 16:47 UTCEPSS rescore
  22. 2026-09-11 14:53 UTCEPSS rescore
  23. 2026-09-10 09:35 UTCEPSS rescore
  24. 2026-09-08 22:01 UTCEPSS rescore
  25. 2026-09-07 16:01 UTCEPSS rescore
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  1. 2026-09-06 13:47 UTCEPSS rescore
  2. 2026-09-04 05:06 UTCEPSS rescore
  3. 2026-09-02 14:12 UTCEPSS rescore
  4. 2026-09-01 13:54 UTCEPSS rescore
  5. 2026-09-01 04:40 UTCEPSS rescore
  6. 2026-08-30 23:41 UTCEG score recompute
  7. 2026-08-30 19:17 UTCEPSS rescore
  8. 2026-08-30 01:22 UTCEPSS rescore
  9. 2026-08-28 21:41 UTCEPSS rescore
  10. 2026-08-27 14:25 UTCEPSS rescore
  11. 2026-08-26 14:46 UTCEPSS rescore
  12. 2026-08-25 13:49 UTCEPSS rescore
  13. 2026-08-24 23:49 UTCEG score recompute
  14. 2026-08-23 10:00 UTCEG score recompute
  15. 2026-08-23 00:19 UTCEPSS rescore
  16. 2026-08-21 23:49 UTCEPSS rescore
  17. 2026-08-21 09:55 UTCEG score recompute
  18. 2026-08-20 22:55 UTCEPSS rescore
  19. 2026-08-20 11:40 UTCEG score recompute
  20. 2026-08-19 17:04 UTCEPSS rescore
  21. 2026-08-19 13:44 UTCEG score recompute
  22. 2026-08-18 13:48 UTCEPSS rescore
  23. 2026-08-17 13:47 UTCEPSS rescore
  24. 2026-08-16 22:49 UTCEG score recompute
  25. 2026-08-16 14:56 UTCEPSS rescore
  26. 2026-08-16 02:14 UTCEPSS rescore
  27. 2026-08-15 23:37 UTCEG score recompute
  28. 2026-08-15 01:30 UTCEPSS rescore
  29. 2026-08-14 01:18 UTCEG score recompute
  30. 2026-08-13 22:00 UTCEPSS rescore
  31. 2026-08-13 03:23 UTCEG score recompute
  32. 2026-08-12 13:51 UTCEPSS rescore
  33. 2026-08-12 05:28 UTCEG score recompute
  34. 2026-08-11 07:33 UTCEG score recompute
  35. 2026-08-11 00:00 UTCEPSS rescore
  36. 2026-08-10 09:38 UTCEG score recompute
  37. 2026-08-09 13:46 UTCEPSS rescore
  38. 2026-08-09 11:44 UTCEG score recompute
  39. 2026-08-08 16:37 UTCEPSS rescore
  40. 2026-08-08 13:45 UTCEG score recompute
  41. 2026-08-06 17:55 UTCEG score recompute
  42. 2026-08-06 13:47 UTCEPSS rescore
  43. 2026-08-05 19:55 UTCEG score recompute
  44. 2026-08-05 19:17 UTCEPSS rescore
  45. 2026-08-04 15:46 UTCEG score recompute
  46. 2026-08-04 15:10 UTCEPSS rescore
  47. 2026-08-04 10:39 UTCEPSS rescore
  48. 2026-08-03 10:36 UTCEPSS rescore
  49. 2026-08-02 07:10 UTCEG score recompute
  50. 2026-08-02 02:27 UTCEPSS rescore
  51. 2026-08-01 09:15 UTCEG score recompute
  52. 2026-08-01 04:16 UTCEPSS rescore
  53. 2026-07-31 04:38 UTCEG score recompute
  54. 2026-07-30 16:28 UTCEPSS rescore
  55. 2026-07-30 06:10 UTCEG score recompute
  56. 2026-07-30 01:30 UTCEPSS rescore
  57. 2026-07-29 04:18 UTCEG score recompute
  58. 2026-07-28 15:37 UTCEPSS rescore
  59. 2026-07-27 18:29 UTCEG score recompute
  60. 2026-07-26 20:34 UTCEG score recompute
  61. 2026-07-26 14:54 UTCEPSS rescore
  62. 2026-07-25 14:18 UTCEPSS rescore
  63. 2026-07-24 14:18 UTCEPSS rescore
  64. 2026-07-23 14:18 UTCEPSS rescore
  65. 2026-07-23 03:18 UTCEG score recompute
  66. 2026-07-22 14:08 UTCEPSS rescore
  67. 2026-07-21 15:25 UTCEPSS rescore
  68. 2026-07-20 17:08 UTCEPSS rescore
  69. 2026-07-19 14:31 UTCEPSS rescore
  70. 2026-07-19 14:31 UTCEPSS rescore
  71. 2026-07-19 02:29 UTCEPSS rescore
  72. 2026-07-18 10:04 UTCEPSS rescore
  73. 2026-07-17 06:14 UTCEG score recompute▲ 1.60
  74. 2026-07-16 17:03 UTCEPSS rescore
  75. 2026-07-15 16:57 UTCEPSS rescore

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-49854?
CVE-2026-49854 is a medium vulnerability published on June 12, 2026. Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided…
When was CVE-2026-49854 disclosed?
CVE-2026-49854 was first published on June 12, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49854 actively exploited?
CVE-2026-49854 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (34th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-49854?
CVE-2026-49854 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-49854?
A fix for CVE-2026-49854 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-49854 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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