CVE-2026-82397

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: 0.4%, top 71% 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
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: None knownExposed: 0

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

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
29%
KEV
Not listed

Published

August 31, 2026

Last Modified

September 9, 2026

Advisory Details (3)

Auto-updated Aug 31, 2026
Patch available. Sources: github_commit, github, github_pr.
github_commit

commit 8d6363ed7b69 (tornadoweb/tornado)

Fix landed in tornadoweb/tornado commit 8d6363ed7b69 — awaiting tagged release

https://github.com/tornadoweb/tornado/commit/8d6363ed7b69d5f0da806efe34d256627a2191de
github_pr

Security 6.5.8

Fix merged in tornadoweb/tornado PR #3704 on 2026-08-07 — awaiting tagged release

https://github.com/tornadoweb/tornado/pull/3704
github Patch Available

Urlencoded body parsing omits max_num_fields, so one request can stall the event loop · Advisory · tornadoweb/tornado · GitHub

https://github.com/tornadoweb/tornado/security/advisories/GHSA-mpf4-983q-p7j4

Vendor Advisories for CVE-2026-82397(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
python-tornado6.2.0-3 ... 6.5.5-5 (24 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
python-tornado6.4.2-3 ... 6.5.5-5 (13 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
python-tornado6.4.2-3 ... 6.5.5-5 (11 versions)——
PyPI(1)
PackageVulnerable rangeFixed inDependents
tornado0.2 ... 6.5b1 (83 versions)6.5.8—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 35× 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. 2026-09-18 22:09 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 20:47 UTCEG score recompute
  4. 2026-09-16 18:43 UTCEG score recompute
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 05:55 UTCEG score recompute
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 04:33 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-15 03:12 UTCEPSS rescore
  11. 2026-09-14 03:11 UTCEG score recompute
  12. 2026-09-13 01:49 UTCEG score recompute
  13. 2026-09-12 00:27 UTCEG score recompute
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-11 11:46 UTCEG score recompute
  17. 2026-09-10 09:51 UTCEG score recompute
  18. 2026-09-08 23:28 UTCEG score recompute
  19. 2026-09-08 22:01 UTCEPSS rescore
  20. 2026-09-08 03:38 UTCEG score recompute
  21. 2026-09-07 00:27 UTCEG score recompute
  22. 2026-09-06 13:48 UTCEPSS rescore
  23. 2026-09-05 23:06 UTCEG score recompute
  24. 2026-09-05 15:31 UTCEPSS rescore
  25. 2026-09-04 21:39 UTCEG score recompute
Show 10 more
  1. 2026-09-04 08:54 UTCEG score recompute
  2. 2026-09-04 05:07 UTCEPSS rescore
  3. 2026-09-02 18:37 UTCEG score recompute
  4. 2026-09-02 17:46 UTCEG score recompute
  5. 2026-09-02 14:12 UTCEPSS rescore
  6. 2026-09-01 23:44 UTCEG score recompute
  7. 2026-09-01 13:54 UTCEPSS rescore
  8. 2026-08-31 22:21 UTCEG score recompute
  9. 2026-08-31 21:35 UTCEG score recompute
  10. 2026-08-31 21:34 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-82397?
CVE-2026-82397 is a high vulnerability published on August 31, 2026. Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parseqs in tornado/escape.py without passing maxnumfields. RequestHandler.execute in tornado/web.py parses the body before handler…
When was CVE-2026-82397 disclosed?
CVE-2026-82397 was first published in the National Vulnerability Database on August 31, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-82397 actively exploited?
CVE-2026-82397 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 71.3% of all scored CVEs.
What is the CVSS score of CVE-2026-82397?
CVE-2026-82397 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-82397?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-82397, 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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