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Random numbers - security issue #369

mworrell opened this Issue Jun 21, 2012 · 1 comment


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mworrell commented Jun 21, 2012

We need to fix our random number/string generation.
At least where it is used for:

  • session ids (all random cookie values)
  • password salts

See this mail from Claes Wikstrom:


New yaws release which contains a fix to pretty serious security hole.
The relevant relnote entry is:

Use crypto:rand_bytes() instead of the cryptographically weak random module. Swedish security consultant and cryptographer Kalle Zetterlund discovered a way to - given a sequence of cookies produced by yaws_session_server - predict the next session id. Thus providing a gaping security hole into yaws servers that use the yaws_session_server to maintain cookie based HTTP sessions (klacke/kallez)

It's been almost 6 months since the last release, so this one also contains
a long series of good fixes and improvements from a lot of good people.

Thanks everyone !!

Code, release, relnotes, docs etc at http://yaws.hyber.org/

Yaws team -


mworrell commented Sep 19, 2012

We need something similar to this patch:


@mworrell mworrell closed this in 5aa11ca Sep 19, 2012

michielklonhammer added a commit to michielklonhammer/zotonic that referenced this issue Sep 25, 2012

rpip pushed a commit to rpip/zotonic that referenced this issue Aug 12, 2013

ddeboer pushed a commit to ddeboer/zotonic that referenced this issue May 16, 2017

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