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CVE-2021-40153

27
FAUCET Score

CVE-2021-40153 describes a path traversal vulnerability in Squashfs-Tools 4.5, affecting various Linux distributions including Debian, Fedora, and Red Hat. The flaw allows an attacker to craft a malicious SquashFS archive that, when unsquashed, can write files to arbitrary locations outside the intended destination directory. With a CVSS score of 8.1 (High), this vulnerability has a low attack complexity and requires user interaction, but can lead to high integrity and availability impacts. Currently, there is no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
4.5CPE matchmatch criteria
cpe:2.3:a:squashfs-tools_project:squashfs-tools:4.5:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.50%
Probability of exploitation in next 30 days
EPSS Percentile
83.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0250 is in the 82nd percentile among its peer group of 14,855 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: 19474-16823Fixed in: 4.5.1-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 4.5.1-1
microsoftpatch availablevia msrc
Product: cbl2 squashfs-tools 4.5.1-1 on CBL Mariner 2.0Fixed in: 4.5.1-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 4.5.1-1
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: squashfs-tools-0:4.3-21.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: squashfs-tools-0:4.4-10.git1.el9
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: squashfs-tools

Vendor Advisories (3)

microsoft2022-Jan/CVE-2021-40153

CVE-2021-40153

Jan 11, 2022
microsoft2021-Aug/CVE-2021-40153Important

squashfs_opendir in unsquash-1.c in Squashfs-Tools 4.5 stores the filename in the directory entry; this is then used by unsquashfs to create the new file during the unsquash. The filename is not validated for traversal outside of the destination directory and thus allows writing to locations outside of the destination.

Aug 10, 2021
redhatCVE-2021-40153Moderate

squashfs-tools: unvalidated filepaths allow writing outside of destination

Sep 10, 2019

References

bugs.launchpad.net / ubuntu/+source/squashfs-tools/+bug/1941790
Third Party Advisory
github.com / plougher/squashfs-tools/commit/79b5a555058eef4e1e7ff220c344d39f8cd09646
PatchThird Party Advisory
github.com / plougher/squashfs-tools/issues/72
ExploitThird Party Advisory
lists.debian.org / debian-lts-announce/2021/08/msg00030.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/GSMRKVJMJFX3MB7D3PXJSYY3TLZROE5S
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/RAOZ4BKWAC4Y3U2K5MMW3S77HWWXHQDL
security.gentoo.org / glsa/202305-29
debian.org / security/2021/dsa-4967
Third Party Advisory