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    CVE-2021-4120

    snapd 2.54.2 fails to perform sufficient validation of snap content interface and layout paths, resulting in the ability for snaps to inject arbitrary AppArmor policy rules via malformed content interface and layout declarations and hence escape strict snap confinement. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1

    Published:Feb 17, 2022
    Last Modified:Nov 21, 2024
    EPS:Feb 17, 2022
    EPSS Score:0.00112
    CVSS Score:8.2

    Affected Products

    Vendor
    Canonical
    Product
    Snapd
    Vendor
    Canonical
    Product
    Ubuntu Linux
    Vendor
    Fedoraproject
    Product
    Fedora

    Exploits

    http://www.openwall.com/lists/oss-security/2022/02/18/2https://bugs.launchpad.net/snapd/+bug/1949368http://www.openwall.com/lists/oss-security/2022/02/18/2https://bugs.launchpad.net/snapd/+bug/1949368

    Common Weakness Enumeration

    CWE-20 Improper Input Validation

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-101 Server Side Include (SSI) Injection
    CAPEC-104 Cross Zone Scripting
    CAPEC-108 Command Line Execution through SQL Injection
    CAPEC-109 Object Relational Mapping Injection
    CAPEC-110 SQL Injection through SOAP Parameter Tampering
    CAPEC-120 Double Encoding
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-135 Format String Injection
    CAPEC-136 LDAP Injection
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-153 Input Data Manipulation
    CAPEC-182 Flash Injection
    CAPEC-209 XSS Using MIME Type Mismatch
    CAPEC-22 Exploiting Trust in Client
    CAPEC-23 File Content Injection
    CAPEC-230 Serialized Data with Nested Payloads
    CAPEC-231 Oversized Serialized Data Payloads
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-250 XML Injection
    CAPEC-261 Fuzzing for garnering other adjacent user/sensitive data
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-28 Fuzzing
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies
    CAPEC-42 MIME Conversion
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-473 Signature Spoof
    CAPEC-52 Embedding NULL Bytes
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-588 DOM-Based XSS
    CAPEC-63 Cross-Site Scripting (XSS)
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-664 Server Side Request Forgery
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-72 URL Encoding
    CAPEC-73 User-Controlled Filename
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-81 Web Server Logs Tampering
    CAPEC-83 XPath Injection
    CAPEC-85 AJAX Footprinting
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities

    Related CVEs

    CVE-2024-29069 (CVSS 4.8) — In snapd versions prior to 2.62, snapd failed to properly check the destination of symbolic links when extract…
    CVE-2024-29068 (CVSS 5.8) — In snapd versions prior to 2.62, snapd failed to properly check the file type when extracting a snap. The snap…
    CVE-2024-1724 (CVSS 6.3) — In snapd versions prior to 2.62, when using AppArmor for enforcement of sandbox permissions, snapd failed to …
    CVE-2020-27352 (CVSS 9.3) — When generating the systemd service units for the docker snap (and other similar snaps), snapd does not specif…
    CVE-2024-5138 (CVSS 8.1) — The snapctl component within snapd allows a confined snap to interact with the snapd daemon to take certain pr…
    CVE-2022-3328 (CVSS 7.8) — Race condition in snap-confine's must_mkdir_and_open_with_perms()…
    CVE-2023-1523 (CVSS 10) — Using the TIOCLINUX ioctl request, a malicious snap could inject contents into the input of the controlling te…
    CVE-2021-44730 (CVSS 7.8) — snapd 2.54.2 did not properly validate the location of the snap-confine binary. A local attacker who can hardl…
    CVE-2021-3155 (CVSS 3.8) — snapd 2.54.2 and earlier created ~/snap directories in user home directories without specifying owner-only per…
    CVE-2021-44731 (CVSS 7.8) — A race condition existed in the snapd 2.54.2 snap-confine binary when preparing a private mount namespace for …

    References

    http://www.openwall.com/lists/oss-security/2022/02/18/2
    https://bugs.launchpad.net/snapd/+bug/1949368
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3QTBN7LLZISXIA4KU4UKDR27Q5PXDS2U/
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XCGHG6LJAVJJ72TMART6A7N4Z6MSTGI7/
    https://ubuntu.com/security/notices/USN-5292-1
    http://www.openwall.com/lists/oss-security/2022/02/18/2
    https://bugs.launchpad.net/snapd/+bug/1949368
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3QTBN7LLZISXIA4KU4UKDR27Q5PXDS2U/
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XCGHG6LJAVJJ72TMART6A7N4Z6MSTGI7/
    https://ubuntu.com/security/notices/USN-5292-1

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High