{"cve":"CVE-2026-55620","nvd":{"published":"2026-08-25T19:16:50.627","modified":"2026-09-09T21:07:31.353","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-770","CWE-1124"],"references":["https://github.com/GOVCERT-LU/eml_parser/commit/746a69f86443eb0b6a47f77db3cfe727c21f92b3","https://github.com/GOVCERT-LU/eml_parser/pull/90","https://github.com/GOVCERT-LU/eml_parser/releases/tag/v3.0.2","https://github.com/GOVCERT-LU/eml_parser/security/advisories/GHSA-g7gc-gmgp-wgqg"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:17.453294893+00:00"},"epss":{"cve":"CVE-2026-55620","score":0.0063,"percentile":0.50189,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-g7gc-gmgp-wgqg","url":"https://osv.dev/vulnerability/GHSA-g7gc-gmgp-wgqg","summary":"eml_parser vulnerable to DoS via deeply nested parens in Received headers","modified":"2026-09-10T12:26:05.568827376Z","packages":[{"ecosystem":"PyPI","name":"eml-parser","purl":"pkg:pypi/eml-parser","ranges":["<3.0.2"],"fixed":["3.0.2"]}]},{"id":"PYSEC-2026-3832","url":"https://osv.dev/vulnerability/PYSEC-2026-3832","summary":"eml_parser vulnerable to DoS via deeply nested parens in Received headers","modified":"2026-09-10T12:15:03.992599275Z","packages":[{"ecosystem":"PyPI","name":"eml-parser","purl":"pkg:pypi/eml-parser","ranges":["<3.0.2"],"fixed":["3.0.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}