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.
History

Wed, 26 Aug 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

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

Updated: 2026-08-26T15:34:18.389Z

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

Link: CVE-2026-55620

cve-icon Vulnrichment

Updated: 2026-08-26T15:34:14.913Z

cve-icon NVD

Status : Deferred

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

Modified: 2026-09-09T21:07:31.353

Link: CVE-2026-55620

cve-icon Redhat

No data.