CVE-2026-103261

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreHIGH confidence

Score 5.3 from GitHub Security Advisory published 2026-10-01. A secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Tornado before 6.5.9 fails to limit the number of query string fields in HTTPServerRequest.__init__, allowing remote attackers to cause event-loop stalling by sending requests with thousands of query parameters. Attackers can send unauthenticated GET requests with unbounded query-string field counts to degrade response times for all clients sharing the same IOLoop.

CVSS v3
5.3
EG Score
5.3MEDIUMhigh confidence
EG Risk
39
EG Risk 39/100CISA SSVC

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%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
38th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 1, 2026

Last Modified

October 1, 2026

Advisory Details (3)

Auto-updated Oct 1, 2026
Patch available. Sources: github_commit, github.
generic

Tornado before 6.5.9 Denial of Service via Query String | Advisories | VulnCheck

https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-query-string
github_commit

commit 03945136ea97 (tornadoweb/tornado)

Fix landed in tornadoweb/tornado commit 03945136ea97 — awaiting tagged release

https://github.com/tornadoweb/tornado/commit/03945136ea9746eccf61caf88edae39642e59c93
github Patch Available

Unbounded query-string argument count allows event-loop-stalling DoS (CWE-770) · Advisory · tornadoweb/tornado · GitHub

https://github.com/tornadoweb/tornado/security/advisories/GHSA-3hv7-mjh2-fv65

Vendor Advisories for CVE-2026-103261(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 12× in last 7d / 12× 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. 2026-10-03 19:23 UTCEG score recompute
  2. 2026-10-03 19:23 UTCGHSA enrichment
  3. 2026-10-03 14:25 UTCEPSS rescore
  4. 2026-10-02 17:25 UTCEG score recompute
  5. 2026-10-02 17:25 UTCGHSA enrichment
  6. 2026-10-01 15:23 UTCEG score recompute
  7. 2026-10-01 15:23 UTCGHSA enrichment
  8. 2026-10-01 14:51 UTCEG score recompute
  9. 2026-10-01 14:51 UTCGHSA enrichment
  10. 2026-10-01 11:27 UTCEG score recompute
  11. 2026-10-01 10:51 UTCEG score recompute
  12. 2026-10-01 10:50 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-103261?
CVE-2026-103261 is a medium vulnerability published on October 1, 2026. Tornado before 6.5.9 fails to limit the number of query string fields in HTTPServerRequest.init, allowing remote attackers to cause event-loop stalling by sending requests with thousands of query parameters. Attackers can send unauthenticated GET requests with unbounded query-string field counts to…
When was CVE-2026-103261 disclosed?
CVE-2026-103261 was first published on October 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-103261 actively exploited?
CVE-2026-103261 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (38th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-103261?
CVE-2026-103261 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-2026-103261?
A fix for CVE-2026-103261 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-103261 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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