How severe is CVE-2026-31958?

CVE-2026-31958 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-31958 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-31958?

CVE-2026-31958 affects Tornadoweb Tornado. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-31958?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-31958 have an EU (EUVD) identifier?

Yes. CVE-2026-31958 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11323.

When was CVE-2026-31958 published?

CVE-2026-31958 was published on 2026-03-11 and last updated on 2026-06-17.

CVE-2026-31958

CVE-2026-31958 is a high-severity vulnerability in Tornadoweb Tornado with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-11323
Weakness: CWE-400
Affected product: Tornadoweb Tornado
Published: 2026-03-11
Last modified: 2026-06-17

Description

Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.

Frequently asked questions

What is CVE-2026-31958?: Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.
How severe is CVE-2026-31958?: CVE-2026-31958 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-31958 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-31958?: CVE-2026-31958 affects Tornadoweb Tornado. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-31958?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-31958 have an EU (EUVD) identifier?: Yes. CVE-2026-31958 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11323.
When was CVE-2026-31958 published?: CVE-2026-31958 was published on 2026-03-11 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:*

More vulnerabilities in Tornadoweb Tornado

CVE-2025-67726 — High (CVSS 7.5): Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient…
CVE-2025-67725 — High (CVSS 7.5): Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, a single…
CVE-2025-47287 — High (CVSS 7.5): Tornado is a Python web framework and asynchronous networking library. When Tornado's ``multipart/form-data`` parser…
CVE-2024-52804 — High (CVSS 7.5): Tornado is a Python web framework and asynchronous networking library. The algorithm used for parsing HTTP cookies in…
CVE-2026-35536 — High (CVSS 7.2): In Tornado before 6.5.5, cookie attribute injection could occur because the domain, path, and samesite arguments to…
CVE-2014-9720 — Medium (CVSS 6.5): Tornado before 3.2.2 sends arbitrary responses that contain a fixed CSRF token and may be sent with HTTP compression,…

All CVEs affecting Tornadoweb Tornado →

Other CWE-400 (Uncontrolled Resource Consumption) vulnerabilities

CVE-2026-46775 — Critical (CVSS 9.9): Vulnerability in Oracle REST Data Services (component: Core). Supported versions that are affected are 24.2.0-26.1.0.…
CVE-2025-61303 — Critical (CVSS 9.8): Hatching Triage Sandbox Windows 10 build 2004 (2025-08-14) and Windows 10 LTSC 2021(2025-08-14) contains a…
CVE-2025-43193 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.6, macOS Sonoma 14.7.7,…
CVE-2025-24269 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.4. An app may be able to…
CVE-2025-24264 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in Safari 18.4, iOS 18.4 and iPadOS 18.4,…
CVE-2025-24260 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.4, macOS Sonoma 14.7.5,…

Browse all CWE-400 (Uncontrolled Resource Consumption) vulnerabilities →