oss-sec mailing list archives

Re: mutt recipient parsing memory leak


From: Utkarsh Gupta <utkarsh () debian org>
Date: Tue, 19 Jan 2021 21:00:46 +0530

Hi Tavis,

On Mon, Jan 18, 2021 at 1:11 AM Tavis Ormandy <taviso () gmail com> wrote:
Hello, I noticed mutt was leaking memory whenever I opened a particular
mailbox. I tracked down the problem: Using rfc822 groups without the madatory
labels wasn't being parsed properly.

https://tools.ietf.org/html/rfc822#section-6.2.6

(A spammer had just put some junk in there, they weren't deliberately using
exotic addressing schemes.. haha).

It turns out that you can send a small message that leaks a *lot* of memory. A
small message can leak GBs of memory, effectively preventing you from opening
your mailbox. You would need to use a different mail client to clean up the
malformed message before you can use mutt again.

I sent this upstream as a DoS, but they don't want to treat it as a security
isssue. I though I'd just send a FYI here instead in case anyone wants to
backport the patch.

Got CVE-2021-3181 assigned for this!


- u


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