1718533 - Thunderbird doesn't render email (blank) if MIME boundary contains apostrophe character

Status: RESOLVED FIXED

(MailNews Core :: Security: OpenPGP, defect)

Description

[Kai Engert [:KaiE:]]

If the MIME boundary of a received email contains an apostrophe character (') then Thunderbird fails to display the email contents. Instead, it shows blank space.

Comment 1

[Kai Engert [:KaiE:]]

According to this answer https://stackoverflow.com/questions/4656287/what-rules-apply-to-mime-boundary
the ' character is allowed in the boundary.

Comment 2

[Kai Engert [:KaiE:]]

Attachment: boundary-with-apostrophe.eml

this message fails to render

Comment 3

[Kai Engert [:KaiE:]]

Attachment: boundary-no-apostrophe.eml

almost the same message as before, just with the apostrophe removed from the boundary, this message renders

Comment 4

[Kai Engert [:KaiE:]]

The implementation for parsing the boundary line is in nsIMIMEHeaderParam::getParameterInternal (mozilla/firefox core code).
Changing component.

Comment 5

[Kai Engert [:KaiE:]]

CC'ing Alfred and Julian who worked on related code in the past.

Comment 6

[Alfred Peters [:infofrommozilla]]

This looks fishy:
https://searchfox.org/comm-central/rev/2211115031808fb4a39e56ee26ec2df93e6bf3b3/mail/extensions/openpgp/content/modules/mimeVerify.jsm#208
this.boundary = hdr.boundary.replace(/['"]/g, "");

I guess this is to remove apostrophes when they are misused as quotation marks. But it also removes them inside the boundary.

Proof: If I remove the apostrophes only in the body, the mail is displayed correctly.

This is a smarter version:
https://searchfox.org/comm-central/rev/2211115031808fb4a39e56ee26ec2df93e6bf3b3/mail/extensions/openpgp/content/modules/fixExchangeMsg.jsm#245
r.boundary = r.boundary.replace(/^(['"])(.*)(['"])/, "$2");

---

See also:
https://searchfox.org/comm-central/rev/2211115031808fb4a39e56ee26ec2df93e6bf3b3/mail/extensions/openpgp/content/modules/mimeEncrypt.jsm#658

Comment 7

[Alfred Peters [:infofrommozilla]]

(In reply to Kai Engert (:KaiE:) from comment #1)

According to this answer https://stackoverflow.com/questions/4656287/what-rules-apply-to-mime-boundary
the ' character is allowed in the boundary.

The original reference:
https://www.rfc-editor.org/rfc/rfc2046#section-5.1.1 -> Page 21

Comment 8

[Alfred Peters [:infofrommozilla]]

Attachment: When the MIME boundary is sanitized, leave apostrophes inside alone

(In reply to Alfred Peters from comment #6)

This is a smarter version:
https://searchfox.org/comm-central/rev/2211115031808fb4a39e56ee26ec2df93e6bf3b3/mail/extensions/openpgp/content/modules/fixExchangeMsg.jsm#245
r.boundary = r.boundary.replace(/^(['"])(.*)(['"])/, "$2");

I have changed all three occurrences so:
.replace(/^(['"])(.*)(\1)$/, "$2");

Only tested with the debuger from the Developer Toolbox. So a trybuild would be useful.

Comment 9

[Kai Engert [:KaiE:]]

Alfred, thanks a lot for finding this code. I didn't expect the OpenPGP code to modify the boundary.

Also I didn't know that it's possible to use the \1 reference expression inside the search string of a regular expression!
That's very useful to know.

I've tested your patch with the original message I've received, and it fixes it correctly.
Thanks for your patch!

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/3806ed03b53b
When the MIME boundary is sanitized, leave apostrophes inside alone r=kaie

Comment 11

[Geoff Lankow (:darktrojan)]

This bug has a target milestone of 91 so I'm setting the status-thunderbird91 flag to fixed.