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CVE-2026-116577

Tornado: Quadratic CPU usage when parsing HTTP headers with line folding

CVSS score

5.3

EPSS probability

—

Risk score

0.5

Published

2 h ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Patch status has not yet been verified

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Vulnerability description

DayBreach AI Explanation

Verified against sources

CVE-2026-116577: Tornado HTTP Header Parsing Vulnerability

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

CVE-2026-116577 is an availability issue in the Tornado Python web framework caused by its HTTP header parser handling line folding. An unauthenticated client can trigger excessive CPU consumption, blocking the IOLoop thread [S0].

Why does it matter?

This vulnerability allows attackers to create denial of service conditions. Since only availability is affected, confidentiality and integrity remain untouched, but ongoing connections can be blocked [S0].

What should be done?

  • Follow vendor advisories and updates [S0]
Chain of evidence and sources2 verified claims

CVE-2026-116577, Tornado sürümlerinde 6.6 öncesinde karesel CPU tüketimine neden olur [S0].

S0 · daybreach-canonical

Kimliği doğrulanmamış istemciler, uygulama kodu çalışmadan önce istek göndererek bağlantıları bloke edebilir [S0].

S0 · daybreach-canonical
Show the technical text from the sources

Tornado is a Python web framework and asynchronous networking library. Prior to 6.6, Tornado's HTTP header parser accepts obsolete line folding and repeatedly concatenates short continuation lines, causing quadratic CPU consumption on the IOLoop thread. An unauthenticated client can submit a header block containing many obsolete line-folding continuations before application code runs, blocking other connections served by the process. The cost grows with max_header_size, and only availability is affected. This issue is fixed in version 6.6.

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CWE: CWE-407, CWE-770

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-116577 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1tornadowebtornado View
Total affected vendors: 1|Products: 1

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
5.3CVSS V3_1MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LCVE CNA
5.3CVSS V31MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LNVD

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-116577 is associated with the following CWEs:

CWE-407: Common Weakness Enumeration Entry CWE-407CWE-770: Allocation of Resources Without Limits or Throttling

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-116577 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

https://github.com/tornadoweb/tornado/security/advisories/GHSA-pcg2-g6cj-q92cvendor-advisoryhttps://github.com/tornadoweb/tornado/pull/3765vendor-advisoryhttps://github.com/tornadoweb/tornado/commit/1b7a1dc9f340f52de929852e8125aa12f25297c9vendor-advisoryhttps://github.com/tornadoweb/tornado/releases/tag/v6.6.0vendor-advisory

CVSS Vector Radar Chart

5.3 / 10
Attack VectorNetworkComplexityLowPrivilegesNoneUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityLow

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)Low

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Follow the vendor

T
tornadoweb logo
tornadoweb

Weakness Type (CWE & CAPEC)

CWE-407 CWE-770

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CVE-2026-116577 · Tornado: Quadratic CPU usage when parsing…