Summary
eml_parser has a URL extraction bypass via HTML entities in URLs
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.
CVE-2026-55618 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.0.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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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.
Frequently Asked Questions
- What is CVE-2026-55618? CVE-2026-55618 is a medium-severity security vulnerability in eml_parser (pip), affecting versions < 3.0.2. It is fixed in 3.0.2.
- How severe is CVE-2026-55618? CVE-2026-55618 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of eml_parser are affected by CVE-2026-55618? eml_parser (pip) versions < 3.0.2 is affected.
- Is there a fix for CVE-2026-55618? Yes. CVE-2026-55618 is fixed in 3.0.2. Upgrade to this version or later.
- Is CVE-2026-55618 exploitable, and should I be worried? Whether CVE-2026-55618 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-55618 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-55618? Upgrade
eml_parserto 3.0.2 or later.