bpo-32981: Fix catastrophic backtracking vulns (#5955)
* Prevent low-grade poplib REDOS (CVE-2018-1060)
The regex to test a mail server's timestamp is susceptible to
catastrophic backtracking on long evil responses from the server.
Happily, the maximum length of malicious inputs is 2K thanks
to a limit introduced in the fix for CVE-2013-1752.
A 2KB evil response from the mail server would result in small slowdowns
(milliseconds vs. microseconds) accumulated over many apop calls.
This is a potential DOS vector via accumulated slowdowns.
Replace it with a similar non-vulnerable regex.
The new regex is RFC compliant.
The old regex was non-compliant in edge cases.
* Prevent difflib REDOS (CVE-2018-1061)
The default regex for IS_LINE_JUNK is susceptible to
catastrophic backtracking.
This is a potential DOS vector.
Replace it with an equivalent non-vulnerable regex.
Also introduce unit and REDOS tests for difflib.
Co-authored-by: Tim Peters <tim.peters@gmail.com>
Co-authored-by: Christian Heimes <christian@python.org>
diff --git a/Misc/ACKS b/Misc/ACKS
index e2addfc..d8179c8 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -356,6 +356,7 @@
Pierre-Yves David
A. Jesse Jiryu Davis
Jake Davis
+Jamie (James C.) Davis
Ratnadeep Debnath
Merlijn van Deen
John DeGood