CVE-2026-55619: eml_parser denial of service via deeply nested email header comments

CVE-2026-55619 · Severity: medium · CVSS 5.3 · Published 2026-08-25

eml_parser is a library used by security operations centers (SOCs) to parse and analyze email messages. An attacker can craft a malicious email with unusually nested comment structures in the header fields (To, From, Cc, etc.) that causes the parser to crash with an unhandled error, preventing the email from being processed. While the impact is limited because organizations already need error handling for malformed emails, it could disrupt automated email analysis pipelines used for threat detection and incident response.

Technologies: GOVCERT-LU Eml Parser, eml-parser (PyPI). Vendors: GOVCERT-LU, PyPI.

Quick answers

Is CVE-2026-55619 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55619 being exploited in the wild.
How severe is CVE-2026-55619?
Medium severity, with a CVSS score of 5.3, published 25 August 2026.
Which products and versions are affected?
GOVCERT-LU Eml Parser < 3.0.2; eml-parser (PyPI) ECOSYSTEM:introduced=0,fixed=3.0.2.
Is there a fix for CVE-2026-55619?
Yes. eml-parser (PyPI): upgrade to 3.0.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55619 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-55619?
Check whether you run GOVCERT-LU Eml Parser or eml-parser (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • eml-parser (PyPI): upgrade to 3.0.2 or later
    pip install "eml-parser>=3.0.2"

Technical details

The vulnerability exists in eml_parser's use of Python's standard library `email.utils.getaddresses()` function to parse email address headers. When processing headers with deeply nested CFWS (comment/folding white space) structures, the standard library's recursive descent parser exhausts the call stack and raises a RecursionError. Since eml_parser does not catch this exception, it propagates uncaught and aborts the entire email message parsing. No authentication or user interaction is required—an attacker simply sends a crafted EML file with pathological header nesting to any SOC pipeline using eml_parser. The fix, released in version 3.0.2, wraps the standard library parser call in error handling and falls back to a simpler regex-based parser when a RecursionError is detected.

Affected products

  • GOVCERT-LU eml_parser < 3.0.2

Identifiers

  • CVE-2026-55619
  • GHSA-m66c-fw79-6359
  • PYSEC-2026-3833

Timeline

  • 2026-06-15: disclosed: Vulnerability initially published in GitHub Advisory Database
  • 2026: patched: Fix released in eml_parser version 3.0.2 with fallback regex-based parser
  • 2026-08-25: advisory: Advisory updated and finalized

References

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