Description
eml_parser serves as a python module for parsing eml files and returning various information found in the e-mail as well as computed information. Prior to 3.0.2, eml_parser.routing.noparenthesis in eml_parser/routing.py removes parenthesized CFWS comments from Received: headers with a regex-based fix-point loop whose running time is quadratic in the nesting depth. A single Received: header with 5,000 nested parentheses causes approximately 1.3 seconds of CPU saturation per parsed message, and doubling the nesting depth approximately quadruples the running time. An attacker can submit relatively small EML files that consume multiple seconds of processing time, causing worker latency, queue backpressure, and possible service-level outages in synchronous gateways, sandboxes, and real-time triage pipelines. This issue is fixed in version 3.0.2.
Published: 2026-08-25
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-g7gc-gmgp-wgqg eml_parser vulnerable to DoS via deeply nested parens in Received headers
History

Tue, 25 Aug 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Govcert-lu
Govcert-lu eml Parser
Vendors & Products Govcert-lu
Govcert-lu eml Parser

Tue, 25 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
Description eml_parser serves as a python module for parsing eml files and returning various information found in the e-mail as well as computed information. Prior to 3.0.2, eml_parser.routing.noparenthesis in eml_parser/routing.py removes parenthesized CFWS comments from Received: headers with a regex-based fix-point loop whose running time is quadratic in the nesting depth. A single Received: header with 5,000 nested parentheses causes approximately 1.3 seconds of CPU saturation per parsed message, and doubling the nesting depth approximately quadruples the running time. An attacker can submit relatively small EML files that consume multiple seconds of processing time, causing worker latency, queue backpressure, and possible service-level outages in synchronous gateways, sandboxes, and real-time triage pipelines. This issue is fixed in version 3.0.2.
Title eml_parser: DoS via deeply nested parens in Received headers
Weaknesses CWE-1124
CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Subscriptions

Govcert-lu Eml Parser
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-25T18:26:54.978Z

Reserved: 2026-06-16T23:31:22.446Z

Link: CVE-2026-55620

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-25T19:16:50.627

Modified: 2026-08-25T19:16:50.627

Link: CVE-2026-55620

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-25T19:30:05Z

Weaknesses