CVE-2025-47287 | Tornado vulnerable to excessive logging caused by malformed multipart form data

Tornado is a Python web framework and asynchronous networking library. When Tornado's ``multipart/form-data`` parser encounters certain errors, it logs a warning but continues trying to parse the remainder of the data. This allows remote attackers to generate an extremely high volume of logs, constituting a DoS attack. This DoS is compounded by the fact that the logging subsystem is synchronous. All versions of Tornado prior to 6.5.0 are affected. The vulnerable parser is enabled by default. Upgrade to Tornado version 6.50 to receive a patch. As a workaround, risk can be mitigated by blocking `Content-Type: multipart/form-data` in a proxy.

Published: 2025-05-15 Last update: 2025-12-23 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-47287 is rated Moderate Risk (58.3/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.16%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-47287

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-11 0.25% 1.16% +0.91%
2 2025-12-28 0.16% 0.25% +0.10%
3 2025-12-27 — 0.16% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-47287

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2025-47287

GitHub Security Advisory for CVE-2025-47287

GHSA-7cx3-6m66-7c5m · Severity: high · Ecosystem: pip — Tornado vulnerable to excessive logging caused by malformed multipart form data

OS Trackers for CVE-2025-47287

vendor priority summary link
debian not yet assigned CVE-2025-47287 not yet assigned priority: Debian including 1 source packages (python-tornado), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-47287
redhat high — https://access.redhat.com/security/cve/CVE-2025-47287
suse high — https://www.suse.com/security/cve/CVE-2025-47287/
ubuntu medium CVE-2025-47287 medium priority: Ubuntu including 1 source packages (python-tornado), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): released 6, ignored 3. https://ubuntu.com/security/CVE-2025-47287

Affected software / configurations for CVE-2025-47287

Vendor Product Version Raw CPE
tornadoweb tornado < 6.5.0 cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-47287

cvelogic Threat Intelligence