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CVE-2024-26151

Potentially untrusted input is rendered as HTML in final output

8.2 HighFix available

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 &lt;script&gt; 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

0.62%Up 0.6 points since Feb 23, 2024
90%50%10%1%

What each source reports

CVE List Score used8.2

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 &lt;script&gt; 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 HighCVSS: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-2024-05188.2

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 &lt;script&gt; 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 HighCVSS: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-62298.2

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 &lt;script&gt; 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 HighCVSS: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
NVD8.2

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 &lt;script&gt; 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 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L
CVSS 3.1
5.4 MediumCVSS: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
OSV8.2

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 &lt;script&gt; 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 HighCVSS: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-62298.2

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 &lt;script&gt; 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 HighCVSS: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-2026-16318.2

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 &lt;script&gt; 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 HighCVSS: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

Affected packages
PackageAffectedFixed
mjml
PyPI
0.10.0 to 0.10.0
0.11.0
mjml
PyPI
0.10.0 up to 0.11.0
0.11.0

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE 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

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