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PYSEC-2026-1300
django-select2Impact
Instances of HeavySelect2Mixin subclasses like the ModelSelect2MultipleWidget and ModelSelect2Widget can secret access tokens across requests. This can allow users to access restricted querysets and restricted data.
Patches
The problem has been patched in version 8.4.1 and all following versions.
Workarounds
This vulnerability is limited use cases where instances of widget classes are created during app loading (not during a request).
Example of affected code:
class MyForm(forms.ModelForm):
class Meta:
widgets = {"my_select_field": Select2ModelWidget()}
Django allows you to pass just the widget class (not the instance). This can be used to mitigate the session request leak.
Example of affected code:
class MyForm(forms.ModelForm):
class Meta:
widgets = {"my_select_field": Select2ModelWidget}
References
Thanks to @neartik for reporting this issue. I will address it later. I had to delete your issue, to avoid exploitation of this security issue.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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