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Debian LTS Advisory DLA-2713-1 debian-lts@lists.debian.org
https://www.debian.org/lts/security/ Ben Hutchings
July 20, 2021 https://wiki.debian.org/LTS
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Package : linux
Version : 4.9.272-2
CVE ID : CVE-2021-3609 CVE-2021-21781 CVE-2021-33909 CVE-2021-34693
Debian Bug : 990072
Brief introduction
CVE-2021-3609
Norbert Slusarek reported a race condition vulnerability in the CAN
BCM networking protocol, allowing a local attacker to escalate
privileges.
CVE-2021-21781
"Lilith >_>" of Cisco Talos discovered that the Arm initialisation
code does not fully initialise the "sigpage" that is mapped into
user-space processes to support signal handling. This could
result in leaking sensitive information, particularly when the
system is rebooted.
CVE-2021-33909
The Qualys Research Labs discovered a size_t-to-int conversion
vulnerability in the Linux kernel's filesystem layer. An
unprivileged local attacker able to create, mount, and then delete a
deep directory structure whose total path length exceeds 1GB, can
take advantage of this flaw for privilege escalation.
Details can be found in the Qualys advisory at
https://www.qualys.com/2021/07/20/cve-2021-33909/sequoia-local-privilege-escalation-linux.txt
CVE-2021-34693
Norbert Slusarek discovered an information leak in the CAN BCM
networking protocol. A local attacker can take advantage of this
flaw to obtain sensitive information from kernel stack memory.
For Debian 9 stretch, these problems have been fixed in version
4.9.272-2.
We recommend that you upgrade your linux packages.
For the detailed security status of linux please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/linux
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
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Ben Hutchings - Debian developer, member of kernel, installer and LTS teams
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