Vulnerabilities in pkg:pypi/eml_parser

PACKAGE
Advisory Identifier: GHSA-g7gc-gmgp-wgqg
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Advisory Summary

CVE-2026-55620 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Eml parser libraries in the PyPI ecosystem. The issue involves eml_parser vulnerable to dos via deeply nested parens in received headers. Remediation is available by upgrading affected packages to version 3.0.2.

4 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:pypi/eml_parser

4 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:pypi/eml_parser. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-g7gc-gmgp-wgqg CVE-2026-55620 HIGH eml_parser vulnerable to DoS via deeply nested parens in Received headers
GHSA-m66c-fw79-6359 CVE-2026-55619 MODERATE eml_parser has parser DoS via deeply nested parentheses in e-mail headers
GHSA-fxgq-9m89-cxj9 CVE-2026-55618 MODERATE eml_parser has a URL extraction bypass via HTML entities in URLs
GHSA-g47v-rwmh-r9f8 CVE-2026-44844 MODERATE eml_parser has recursion DoS via nested message/rfc822 attachments

CVE-2026-55620 at a Glance

CVE Identifier CVE-2026-55620
GHSA Identifier GHSA-g7gc-gmgp-wgqg
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Eml parser
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-55620

To remediate this vulnerability, upgrade all affected Eml parser dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

eml_parser fixed: 3.0.2 
pip install eml_parser>=3.0.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show eml_parser

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-55620, inspect your installed packages using pip:

pip show eml_parser

Analyze the terminal output to locate any version of Eml parser in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.0.2), your application is affected.

Note: The pip show eml_parser command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Eml parser, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary `eml_parser` strips parenthesised CFWS comments from `Received:` headers using a regex-based fix-point loop. The loop has quadratic time complexity in the number of nested parens. A single `Received:` header containing 5,000 nested parens causes ~1.3 seconds of CPU saturation per parsed message; runtime quadruples per doubling of nesting depth. ### Impact This represents a CPU exhaustion DoS in any pipeline that processes attacker-supplied EML files. An attacker can create relatively small EML files that will take multiple seconds to parse. This is particularly problematic for synchronous email-processing pipelines (gateways, sandboxes, real-time triage) where worker latency directly translates to queue backpressure and possible service-level outages. ### Patches Since version 3.0.2, `eml_parser` uses a linear-time algorithm to remove the comments from `Received:` headers.

CVE-2026-55620 Affected Eml parser Versions

1 component(s)
Fixed Versions:
3.0.2
Product / Package Ecosystem Affected Versions Fixed Version
eml_parser
pypi/eml_parser
PyPI
< 3.0.2
3.0.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/GOVCERT-LU/eml_parser/security/advisories/GHSA-g7gc-gmgp-wgqg
Eml parser Source Repository REPOSITORY
https://github.com/GOVCERT-LU/eml_parser/pull/90
Security Fix Commit FIX COMMIT
https://github.com/GOVCERT-LU/eml_parser/commit/746a69f86443eb0b6a47f77db3cfe727c21f92b3
Eml parser Source Repository REPOSITORY
https://github.com/GOVCERT-LU/eml_parser
Eml parser Release RELEASE
https://github.com/GOVCERT-LU/eml_parser/releases/tag/v3.0.2

Frequently Asked Questions

What is CVE-2026-55620?
CVE-2026-55620 is a security vulnerability in Eml parser involving eml_parser vulnerable to DoS via deeply nested parens in Received headers under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Eml parser versions are affected?
Affected versions include releases prior to 3.0.2 across affected packages: eml_parser.
What version fixes CVE-2026-55620?
Upgrading to 3.0.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is eml_parser affected?
Yes, eml_parser is affected in releases prior to 3.0.2. Upgrade your dependency to 3.0.2 or later.
What is the CVSS score of CVE-2026-55620?
CVE-2026-55620 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-55620?
CVE-2026-55620 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check PyPI dependencies for CVE-2026-55620?
Run the dependency tree command: 'pip show eml_parser'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-g7gc-gmgp-wgqg",
  "modified" : "2026-08-25T18:27:18Z",
  "published" : "2026-08-25T18:27:18Z",
  "aliases" : [ "CVE-2026-55620" ],
  "summary" : "eml_parser vulnerable to DoS via deeply nested parens in Received headers",
  "details" : "### Summary\n\n`eml_parser` strips parenthesised CFWS comments from `Received:` headers using a regex-based fix-point loop. The loop has quadratic time complexity in the number of nested parens. A single `Received:` header containing 5,000 nested parens causes ~1.3 seconds of CPU saturation per parsed message; runtime quadruples per doubling of nesting depth.\n\n### Impact\n\nThis represents a CPU exhaustion DoS in any pipeline that processes attacker-supplied EML files. An attacker can create relatively small EML files that will take multiple seconds to parse.\n\nThis is particularly problematic for synchronous email-processing pipelines (gateways, sandboxes, real-time triage) where worker latency directly translates to queue backpressure and possible service-level outages.\n\n### Patches\n\nSince version 3.0.2, `eml_parser` uses a linear-time algorithm to remove the comments from `Received:` headers.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "eml_parser"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/GOVCERT-LU/eml_parser/security/advisories/GHSA-g7gc-gmgp-wgqg"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/GOVCERT-LU/eml_parser/pull/90"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/GOVCERT-LU/eml_parser/commit/746a69f86443eb0b6a47f77db3cfe727c21f92b3"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/GOVCERT-LU/eml_parser"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/GOVCERT-LU/eml_parser/releases/tag/v3.0.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1124", "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-25T18:27:18Z",
    "nvd_published_at" : null
  }
}