A libgit2 security update has been released for Debian GNU/Linux 9 LTS to address multiple vulnerabilities.

DLA 2936-1: libgit2 security update

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Debian LTS Advisory DLA-2936-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Utkarsh Gupta
March 07, 2022   https://wiki.debian.org/LTS
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Package : libgit2
Version : 0.25.1+really0.24.6-1+deb9u1
CVE ID : CVE-2018-8098 CVE-2018-8099 CVE-2018-10887 CVE-2018-10888
CVE-2018-15501 CVE-2020-12278 CVE-2020-12279
Debian Bug : 892961 892962 903508 903509

Multiple vulnerabilities were found in libgit2, a low-level Git library,
and are as follows:

CVE-2018-8098

Integer overflow in the index.c:read_entry() function while
decompressing a compressed prefix length in libgit2 before
v0.26.2 allows an attacker to cause a denial of service
(out-of-bounds read) via a crafted repository index file.

CVE-2018-8099

Incorrect returning of an error code in the index.c:read_entry()
function leads to a double free in libgit2 before v0.26.2, which
allows an attacker to cause a denial of service via a crafted
repository index file.

CVE-2018-10887

It has been discovered that an unexpected sign extension in
git_delta_apply function in delta-apply.c file may lead to an
integer overflow which in turn leads to an out of bound read,
allowing to read before the base object. An attacker may use
this flaw to leak memory addresses or cause a Denial of Service.

CVE-2018-10888

A missing check in git_delta_apply function in delta-apply.c file,
may lead to an out-of-bound read while reading a binary delta file.
An attacker may use this flaw to cause a Denial of Service.

CVE-2018-15501

In ng_pkt in transports/smart_pkt.c in libgit2, a remote attacker
can send a crafted smart-protocol "ng" packet that lacks a '\0'
byte to trigger an out-of-bounds read that leads to DoS.

CVE-2020-12278

path.c mishandles equivalent filenames that exist because of NTFS
Alternate Data Streams. This may allow remote code execution when
cloning a repository. This issue is similar to CVE-2019-1352.

CVE-2020-12279

checkout.c mishandles equivalent filenames that exist because of
NTFS short names. This may allow remote code execution when cloning
a repository. This issue is similar to CVE-2019-1353.

For Debian 9 stretch, these problems have been fixed in version
0.25.1+really0.24.6-1+deb9u1.

We recommend that you upgrade your libgit2 packages.

For the detailed security status of libgit2 please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/libgit2

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