eml_parser has a URL extraction bypass via HTML entities in URLs

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-55618: 0.52% estimated exploitation activity in the next 30 days; percentile 43.93 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary emlparser 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 emlparser 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…

Published by the source

25 Aug 2026, 18:23 UTC

Last modified by the source

25 Aug 2026, 18:23 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fxgq-9m89-cxj9

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# Patch Next advisory brief: CVE-2026-55618

Advisory: eml_parser has a URL extraction bypass via HTML entities in URLs
IDs: CVE-2026-55618, GHSA-fxgq-9m89-cxj9
Record: https://patchnext.com/advisories/cve-2026-55618 (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: eml-parser 3.0.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI eml-parser: affected < 3.0.2; fixed in 3.0.2

## Suggested inspection (read-only)
- `python -m pip show eml-parser`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on eml-parser.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fxgq-9m89-cxj9 (GitHub-reviewed advisory GHSA-fxgq-9m89-cxj9 lists affected ranges: PyPI eml-parser >=0 <3.0.2)

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