Secunia Research Advisory

Linux Kernel "sctp_sendmsg()" Use-After-Free Vulnerability


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                     Secunia Research 2019/02/21
      Linux Kernel "sctp_sendmsg()" Use-After-Free Vulnerability
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Table of Contents
Affected Software....................................................1
Severity.............................................................2
Description of Vulnerability.........................................3
Solution.............................................................4
Time Table...........................................................5
Credits..............................................................6
References...........................................................7
About Flexera .......................................................8
Verification.........................................................9
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1) Affected Software
* Linux Kernel versions 4.20.x and 4.19.x.
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2) Severity
Rating: Less critical
Impact: Privilege escalation
Where: Local System
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3) Description of Vulnerability
Secunia Research has discovered a vulnerability in Linux Kernel, which
can be exploited by malicious, local users to potentially gain
escalated privileges.
A use-after-free error in the "sctp_sendmsg()" function
(net/sctp/socket.c) when handling SCTP_SENDALL flag can be exploited
to corrupt memory.
The vulnerability is confirmed in version 4.20.0-rc2 and reported
in versions 4.20.x prior to 4.20.8 and 4.19.x prior to 4.19.21.
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4) Solution
Update to version 4.20.8 or 4.19.21.
https://git.kernel.org/linus/ba59fb0273076637f0add4311faa990a5eec27c0
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5) Time Table
2019/02/01 - Linux Kernel team contacted with vulnerability details.
2019/02/01 - Linux Kernel team confirmed the vulnerability.
2019/02/10 - Release of the official patch.
2019/02/21 - Release of Secunia Advisory SA87000.
2019/02/21 - Public disclosure of Secunia Research Advisory.
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6) Credits
Jakub Jirasek, Secunia Research at Flexera.
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7) References
The Flexera CNA has assigned CVE-2019-8956 identifier for the
vulnerability through the Common Vulnerabilities and Exposures (CVE)
project.
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8) About Flexera
Flexera helps application producers and enterprises increase
application usage and the value they derive from their software.
http://www.flexera.com
Flexera delivers market-leading Software Vulnerability Management
solutions enabling enterprises to proactively identify and
remediate software vulnerabilities, effectively reducing the risk of
costly security breaches.
https://www.flexera.com/enterprise/products/
Flexera supports and contributes to the community in several
ways. We have always believed that reliable vulnerability
intelligence and tools to aid identifying and fixing vulnerabilities
should be freely available for consumers to ensure that users,
who care about their online privacy and security, can stay secure.
Only a few vendors address vulnerabilities in a proper way and help
users get updated and stay secure. End-users (whether private
individuals or businesses) are otherwise left largely alone, and
that is why back in 2002, Secunia Research started investigating,
coordinating disclosure and verifying software vulnerabilities.
In 2016, Secunia Research became a part of Flexera and today
our in-house software vulnerability research remains the core of
the Software Vulnerability Management products at Flexera.
https://www.flexera.com/enterprise/company/about/secunia-research/
The public Secunia Advisory database contains information for
researchers, security enthusiasts, and consumers to lookup individual
products and vulnerabilities and assess, whether they need to take
any actions to secure their systems or whether a given vulnerability
has already been discovered
https://www.flexera.com/company/secunia-research/advisories/
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9) Verification
Please verify this advisory by visiting the Secunia Research website:
https://www.flexera.com/products/operations/software-vulnerability-research/secunia-research/advisories/sr-2019-05.html
Complete list of vulnerability reports published by Secunia Research:
https://www.flexera.com/company/secunia-research/advisories/