CVE-2026-55618: Eml parser Eml_parser Has A URL Extraction Vulnerability

MODERATE
Advisory Identifier: GHSA-fxgq-9m89-cxj9
Share
CVSS 6.5
CWE-116
Published
Advisory Summary

CVE-2026-55618 is a MODERATE (CVSS 6.5) eml_parser has a url extraction vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting Eml parser libraries in the PyPI ecosystem. The issue involves eml_parser has a url extraction bypass via html entities in urls. Remediation is available by upgrading affected packages to version 3.0.2.

CVE-2026-55618 at a Glance

CVE Identifier CVE-2026-55618
GHSA Identifier GHSA-fxgq-9m89-cxj9
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-116: Improper Encoding or Escaping of Output
Affected Product Eml parser
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.5

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:R/S:U/C:N/I:H/A:N).

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

How to Fix CVE-2026-55618

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-2026-55618, 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-116: Improper Encoding or Escaping of Output, where the product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. as a result, the intended structure of the message is not preserved. 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` performs certain validations on potential URL strings to discard bogus values. In versions prior to `3.0.2`, this validation was performed before unescaping any HTML entities that might occur in the string. This caused the library to wrongfully reject valid URLs that use HTML entities for the `:`, `/`, or `.` characters. These URLs would then not be included in the list of extracted URLs. Similarly, the host parts of such URLs would not be extracted. For example, neither the URL `https://phishing.example.com` nor its host (`phishing.example.com`) would appear in the parsing result. ## Impact `eml_parser` is used in email security gateways and SOC pipelines to extract URLs as IOCs. Those URLs are then checked against threat-intel feeds, URL reputation services, and sandboxes. A URL that is not extracted is never checked. ## Patches Since version 3.0.2 the library unescapes all HTML entities in every URL before deciding to accept or reject it. A test was added to prevent regressions.

CVE-2026-55618 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-fxgq-9m89-cxj9
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-2026-55618?
CVE-2026-55618 is a security vulnerability in Eml parser involving eml_parser has a URL extraction bypass via HTML entities in URLs under CWE-116: Improper Encoding or Escaping of Output.
Which Eml parser versions are affected?
Affected versions include releases prior to 3.0.2 across affected packages: eml_parser.
What version fixes CVE-2026-55618?
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-2026-55618?
CVE-2026-55618 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-55618?
CVE-2026-55618 is classified under CWE-116: Improper Encoding or Escaping of Output (The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.).
How can I check PyPI dependencies for CVE-2026-55618?
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-fxgq-9m89-cxj9",
  "modified" : "2026-08-25T18:23:16Z",
  "published" : "2026-08-25T18:23:16Z",
  "aliases" : [ "CVE-2026-55618" ],
  "summary" : "eml_parser has a URL extraction bypass via HTML entities in URLs",
  "details" : "## Summary\n\n`eml_parser` performs certain validations on potential URL strings to discard bogus values. In versions prior to `3.0.2`, this validation was performed before unescaping any HTML entities that might occur in the string. This caused the library to wrongfully reject valid URLs that use HTML entities for the `:`, `/`, or `.` characters. These URLs would then not be included in the list of extracted URLs. Similarly, the host parts of such URLs would not be extracted.\n\nFor example, neither the URL `https&#58;&#47;&#47;phishing&#46;example&#46;com` nor its host (`phishing.example.com`) would appear in the parsing result.\n\n## Impact\n\n`eml_parser` is used in email security gateways and SOC pipelines to extract URLs as IOCs. Those URLs are then checked against threat-intel feeds, URL reputation services, and sandboxes. A URL that is not extracted is never checked.\n\n## Patches\n\nSince version 3.0.2 the library unescapes all HTML entities in every URL before deciding to accept or reject it. A test was added to prevent regressions.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"
  } ],
  "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-fxgq-9m89-cxj9"
  }, {
    "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-116" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-25T18:23:16Z",
    "nvd_published_at" : null
  }
}