django.utils.text.wrap does not preserve newlines within text to be wrapped

[Matti Pohjanvirta]

After the fix for CVE-2025-26699, django.utils.text.wrap and wordwrap template filter no longer preserve empty lines in between lines in a text that is wrapped.

Given a text with an intentional empty line between paragraphs to wrap:

First line

Second line

it is wrapped to:

First line
Second line

[Natalia Bidart]

Hello Matti Pohjanvirta, thank you very much for taking the time to create this report. I can confirm this is a regression in 55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b. I will review your patch shortly, could you please double check that the patch does not add any exploitable performance issues?

[Natalia Bidart]

Related ​forum post.

[nessita <124304+nessita@…>]

In 1e9db35:

Fixed #36341 -- Preserved whitespaces in wordwrap template filter.

Regression in 55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b.

This work improves the django.utils.text.wrap() function to ensure that
empty lines and lines with whitespace only are kept instead of being
dropped.

Thanks Matti Pohjanvirta for the report and fix.

Co-authored-by: Natalia <124304+nessita@…>

[Natalia <124304+nessita@…>]

In 305aa4d0:

[5.2.x] Fixed #36341 -- Preserved whitespaces in wordwrap template filter.

Regression in 55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b.

This work improves the django.utils.text.wrap() function to ensure that
empty lines and lines with whitespace only are kept instead of being
dropped.

Thanks Matti Pohjanvirta for the report and fix.

Co-authored-by: Natalia <124304+nessita@…>

Backport of 1e9db35836d42a3c72f3d1015c2f302eb6fee046 from main.

[Natalia Bidart]

After the PR merge I realized we need to backport this to 5.1 and 4.2 as well, I'll be preparing a PR with releases notes and backport both revisions.

[GitHub <noreply@…>]

In c86242d6:

Refs #36341 -- Added release notes for 5.1.9 and 4.2.21 for fix in wordwrap template filter.

Revision 1e9db35836d42a3c72f3d1015c2f302eb6fee046 fixed a regression in
55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b, which also needs to be
backported to the stable branches in extended support (5.1.x and 4.2.x).

[Natalia <124304+nessita@…>]

In 7d80f70:

[5.2.x] Refs #36341 -- Added release notes for 5.1.9 and 4.2.21 for fix in wordwrap template filter.

Revision 1e9db35836d42a3c72f3d1015c2f302eb6fee046 fixed a regression in
55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b, which also needs to be
backported to the stable branches in extended support (5.1.x and 4.2.x).

Backport of c86242d61ff81bddbead115c458c1eb532d43b43 from main.

[Natalia <124304+nessita@…>]

In 09a1813:

[5.1.x] Fixed #36341 -- Preserved whitespaces in wordwrap template filter.

Regression in 55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b.

This work improves the django.utils.text.wrap() function to ensure that
empty lines and lines with whitespace only are kept instead of being
dropped.

Thanks Matti Pohjanvirta for the report and fix.

Co-authored-by: Natalia <124304+nessita@…>

Backport of 1e9db35836d42a3c72f3d1015c2f302eb6fee046 from main.

[Natalia <124304+nessita@…>]

In 660067f8:

[5.1.x] Refs #36341 -- Added release notes for 5.1.9 and 4.2.21 for fix in wordwrap template filter.

Revision 1e9db35836d42a3c72f3d1015c2f302eb6fee046 fixed a regression in
55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b, which also needs to be
backported to the stable branches in extended support (5.1.x and 4.2.x).

Backport of c86242d61ff81bddbead115c458c1eb532d43b43 from main.

[Natalia <124304+nessita@…>]

In e61e3daa:

[4.2.x] Fixed #36341 -- Preserved whitespaces in wordwrap template filter.

Regression in 55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b.

This work improves the django.utils.text.wrap() function to ensure that
empty lines and lines with whitespace only are kept instead of being
dropped.

Thanks Matti Pohjanvirta for the report and fix.

Co-authored-by: Natalia <124304+nessita@…>

Backport of 1e9db35836d42a3c72f3d1015c2f302eb6fee046 from main.

[Natalia <124304+nessita@…>]

In b3df753:

[4.2.x] Refs #36341 -- Added release note for 4.2.21 for fix in wordwrap template filter.

Revision 1e9db35836d42a3c72f3d1015c2f302eb6fee046 fixed a regression in
55d89e25f4115c5674cdd9b9bcba2bb2bb6d820b, which also needs to be
backported to the stable branches in extended support.

Backport of c86242d61ff81bddbead115c458c1eb532d43b43 from main.