Eventlet affected by HTTP request smuggling in unparsed trailers (CVE-2025-58068)
Published Last modified Sources: Red Hat, BSI, CVE.org, OSV
What is affected, what to do
Eventlet is a concurrent networking library for Python. Prior to version 0.40.3, the Eventlet WSGI parser is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer sections.
Update Eventlet to version 0.40.3.
- Affected
- Eventlet
lt *..0.40.3
- Eventlet
- Fixed in
- Eventlet
0.40.3
- Eventlet
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Metrics
9.1
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
9.1
CVSS v3
Severity Critical on the scale from 0 to 10.
Source: Red Hat, BSI, CVE.org, OSV
0.4 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 31.6
Show all metrics
- Severity
- Critical
Priority score
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 64.23
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 9.1
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 9.1
CVSS v4
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 6.3
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.4 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 31.6
- Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-444
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Eventlet is a concurrent networking library for Python. Prior to version 0.40.3, the Eventlet WSGI parser is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer sections. This vulnerability could enable attackers to, bypass front-end security controls, launch targeted attacks against active site users, and poison web caches. This problem has been patched in Eventlet 0.40.3 by dropping trailers which is a breaking change if a backend behind eventlet.wsgi proxy requires trailers. A workaround involves not using eventlet.wsgi facing untrusted clients.
Source: redhat_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), cvelistv5, CVE.org (MITRE), OSV (Open Source Vulnerabilities)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| eventlet | eventlet |
|
|
| pypi | eventlet |
|
|
Weakness classes (CWE)
CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Base
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
Entry at MITRE CWE-444
References & sources
- github.comeventlet/eventlet/security/advisories/GHSA-hw6f-rjfj-j7j7web, x_refsource_CONFIRM, Vendor advisory
- NVD (NIST)vuln/detail/CVE-2025-58068advisory
- github.comeventlet/eventlet/pull/1062web, x_refsource_MISC, Issue tracking
- github.comeventlet/eventlet/commit/0bfebd1117d392559e25b4bfbfcc941754de88…web, x_refsource_MISC, Patch
- github.comeventlet/eventletpackage
- lists.debian.orgdebian-lts-announce/2025/09/msg00003.htmlweb
Reanalysis & status changes
Chronological NVD audit events for this CVE — reanalyses, CVSS updates, CPE diffs.
CVE Translatednvd@nist.gov
- Translation: after Title: Eventlet, Description: Eventlet es una biblioteca de red concurrente para Python. Antes de la versión 0.40.3, el analizador WSGI de Eventlet es vulnerable a Contrabando de Solicitudes HTTP debido a un manejo inadecuado de las secciones de tráiler HTTP. Esta vulnerabilidad podría permitir a los atacantes eludir los controles de seguridad de front-end, lanzar ataques dirigidos contra usuarios activos del sitio y envenenar las cachés web. Este problema ha sido parcheado en Eventlet 0.40.3 eliminando los tráilers, lo cual es un cambio disruptivo si un backend detrás de un proxy eventlet.wsgi requiere tráilers. Una solución alternativa implica no usar eventlet.wsgi frente a clientes no confiables.