Bug 1277339 - (CVE-2015-4518) CVE-2015-4518 Mozilla: CSP bypass due to permissive Reader mode whitelist (MFSA 2015-118)
CVE-2015-4518 Mozilla: CSP bypass due to permissive Reader mode whitelist (MF...
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
: Security
Depends On:
Blocks: 1275590
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Reported: 2015-11-03 00:45 EST by Huzaifa S. Sidhpurwala
Modified: 2015-11-03 23:57 EST (History)
1 user (show)

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Doc Type: Bug Fix
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Last Closed: 2015-11-03 23:57:40 EST
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Description Huzaifa S. Sidhpurwala 2015-11-03 00:45:45 EST
Security researcher Mario Heiderich reported an issue where the security protections of Reader mode in Firefox can be bypassed, allowing scripts to be run. Mozilla developer Frederik Braun independently discovered and reported this same issue as well. This issue happens even though Reader View explicitly disables script for rendered pages through a whitelist of allowed HTML content. Mario discovered that the whitelist was too permissive and a malicious site could manipulate content to bypass CSP protections, allowing for possible cross-site scripting (XSS) attacks.

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Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Mario Heiderich as the original reporter.


This issue does not affect the version of firefox and thunderbird as shipped with Red Hat Enterprise Linux 5, 6 and 7.

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