BAN-B308 · Audit required: Use of `mark

Audit required: Use of mark_safe detected BAN-B308

Security

Major

20 days ago — 4 years old

Use of mark_safe() may expose cross-site scripting vulnerabilities and should be reviewed.

 223            GROUP_TEMPLATE,
 224            [
 225                (
 226                    mark_safe('data-toggle="buttons"'),  # noqa: S308 227                    rtl_switch,
 228                )
 229            ],  # Only one group.

Use of mark_safe() may expose cross-site scripting vulnerabilities and should be reviewed.

weblate/trans/forms.py

 205                    gettext("Toggle text direction"),
 206                    rtl_name,
 207                    "rtl",
 208                    mark_safe('checked="checked"'),  # noqa: S308 209                    "RTL",
 210                ),
 211                (

Use of mark_safe() may expose cross-site scripting vulnerabilities and should be reviewed.

weblate/trans/forms.py

 172                    name,
 173                    format_html(
 174                        'data-value="{}"',
 175                        mark_safe(  # noqa: S308 176                            value.encode("ascii", "xmlcharrefreplace").decode("ascii") 177                        ), 178                    ),
 179                    char,
 180                )

Use of mark_safe() may expose cross-site scripting vulnerabilities and should be reviewed.

weblate/trans/forms.py

 244                    name,
 245                    format_html(
 246                        'data-value="{}"',
 247                        mark_safe(  # noqa: S308 248                            value.encode("ascii", "xmlcharrefreplace").decode("ascii") 249                        ), 250                    ),
 251                    char,
 252                )

Use of mark_safe() may expose cross-site scripting vulnerabilities and should be reviewed.

weblate/checks/format.py

424            errors.extend(self.format_result(results))
425        if errors:
426            return format_html_join(
427                mark_safe("<br />"),  # noqa: S308428                "{}",
429                ((error,) for error in errors),
430            )

Description

Use of mark_safe() may expose cross-site scripting (XSS) vulnerabilities and should be reviewed. mark_safe explicitly marks a string as safe for (HTML) output purposes.

Django auto-escapes all output from template variable tags unless explicitly told not to. Use of mark_safe() function implies that the parameter is safe for client-side output without Django's automatic string escaping. It's a legitimate way of defining strings that are intended to be interpreted as HTML.

Using mark_safe() on an internally generated string is okay but becomes a security risk if used on unchecked user input.

Since this is an audit issue, some occurrences may be harmless here. The goal is to bring the issue to attention. Please make sure that the input string is trusted. If the occurrences don't seem to be valid, please feel free to ignore them.

When possible, use formathtml. It is safe as all arguments are passed through conditionalescape()

Bad practice

mark_safe("<b>%s</b> %s" % (user_input))

References:

mark_safe
OWASP Top 10 2021 Category A03 - Injection
CWE 79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

WeblateOrg / weblate

Bad practice

Recommended

References: