CVE-2024-26151
Potentially untrusted input is rendered as HTML in final output
The mjml PyPI package, found at the FelixSchwarz/mjml-python GitHub repo, is an unofficial Python port of MJML, a markup language created by Mailjet. All users of FelixSchwarz/mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output. The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform. The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue. As a workaround, ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- High
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used 8.2
Potentially untrusted input is rendered as HTML in final output
The mjml PyPI package, found at the FelixSchwarz/mjml-python GitHub repo, is an unofficial Python port of MJML, a markup language created by Mailjet. All users of FelixSchwarz/mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output. The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform. The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue. As a workaround, ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
- Record
CVE-2024-26151- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Weakness
- CWE-20
- Updated
- 2026-11-02
EUVDEUVD-2024-0518 8.2
The mjml PyPI package, found at the FelixSchwarz/mjml-python GitHub repo, is an unofficial Python port of MJML, a markup language created by Mailjet. All users of FelixSchwarz/mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output. The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform. The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue. As a workaround, ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
- Record
EUVD-2024-0518- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-578p-fxmm-6229 8.2
Potentially untrusted input is rendered as HTML in final output
Impact
All users of mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output.
The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform.
Patches
The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue which was added as part of commit 84c495da20a91640a1ca551ace17df7f3be644aa.
Workarounds
- Ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
References
- Initial issue report by @sh-at-cs in #52
- Record
GHSA-578p-fxmm-6229- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Weakness
- CWE-20, CWE-79
- Updated
- 2026-11-02
NVD 8.2
The mjml PyPI package, found at the FelixSchwarz/mjml-python GitHub repo, is an unofficial Python port of MJML, a markup language created by Mailjet. All users of FelixSchwarz/mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output. The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform. The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue. As a workaround, ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
- Record
CVE-2024-26151- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-20, CWE-79
- Updated
- 2026-11-02
OSV 8.2
Potentially untrusted input is rendered as HTML in final output
The mjml PyPI package, found at the FelixSchwarz/mjml-python GitHub repo, is an unofficial Python port of MJML, a markup language created by Mailjet. All users of FelixSchwarz/mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output. The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform. The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue. As a workaround, ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
- Record
CVE-2024-26151- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Weakness
- CWE-20
- Updated
- 2026-11-02
OSVGHSA-578p-fxmm-6229 8.2
Potentially untrusted input is rendered as HTML in final output
Impact
All users of mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output.
The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform.
Patches
The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue which was added as part of commit 84c495da20a91640a1ca551ace17df7f3be644aa.
Workarounds
- Ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
References
- Initial issue report by @sh-at-cs in #52
- Record
GHSA-578p-fxmm-6229- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Weakness
- CWE-20, CWE-79
- Updated
- 2026-11-02
OSVPYSEC-2026-1631 8.2
Potentially untrusted input is rendered as HTML in final output
Impact
All users of mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output.
The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform.
Patches
The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue which was added as part of commit 84c495da20a91640a1ca551ace17df7f3be644aa.
Workarounds
- Ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
References
- Initial issue report by @sh-at-cs in #52
- Record
PYSEC-2026-1631- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-26151 is a high vulnerability (CVSS 8.2) in Felixschwarz Mjml-python, published February 22, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.62%, the 50th percentile. Fixed in mjml 0.11.0.
References
github.com/FelixSchwarz/mjml-python/security/advisories/GHSA-578p-fxmm-6229
github.com/FelixSchwarz/mjml-python/issues/52
github.com/FelixSchwarz/mjml-python/commit/84c495da20a91640a1ca551ace17df7f3be644aa
github.com/FelixSchwarz/mjml-python/commit/8d410b7a500703080bb14ed7e3d2663fe16767e6
github.com/FelixSchwarz/mjml-python/releases/tag/v0.11.0
vicarius.io/vsociety/posts/cve-2024-26151-mjml-python-vulnerability-1