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Ubuntu LinuxOperating system · Canonical

CVE-2020-11934

MEDIUM · 5.9 CVSS v3.1 Published 2020-07-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
It was discovered that snapctl user-open allowed altering the $XDG_DATA_DIRS environment variable when calling the system xdg-open. OpenURL() in usersession/userd/launcher.go would alter $XDG_DATA_DIRS to append a path to a directory controlled by the calling snap. A malicious snap could exploit this to bypass intended access restrictions to control how the host system xdg-open script opens the URL and, for example, execute a script shipped with the snap without confinement. This issue did not affect Ubuntu Core systems. Fixed in snapd versions 2.45.1ubuntu0.2, 2.45.1+18.04.2 and 2.45.1+20.04.2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The snapctl user-open command in snapd allowed a malicious snap to manipulate the $XDG_DATA_DIRS environment variable by appending a snap-controlled directory path. This enabled the snap to influence which xdg-open script gets executed when opening URLs, potentially allowing execution of confined snap scripts without proper sandboxing restrictions.

MitigationUpdate snapd to version 2.45.1ubuntu0.2 (Ubuntu), 2.45.1+18.04.2 (18.04), or 2.45.1+20.04.2 (20.04) to remediate the vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ubuntu LinuxOperating system
Affected:= 16.04= 18.04= 19.10= 20.04

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify snapd is installed
    Run: which snapd or dpkg -l | grep snapd or snap --version
    Affected if snapd is not installed on the system (not vulnerable)
  2. Check snapd version
    Run: snapd --version
    Affected if The installed version is 2.45.1 or lower (vulnerable)
  3. Query snapd service status
    Run: systemctl status snapd.service (systemd) or service snapd status
    Affected if Service is running with a vulnerable version
  4. Check snap version as fallback
    Run: snap version to see snap and snapd versions together
    Affected if The snapd component version shown is 2.45.1 or lower

A system is affected if snapd is installed and running with version 2.45.1 or lower on Ubuntu 16.04, 18.04, 19.10, or 20.04, because the snapctl user-open command in these versions allows $XDG_DATA_DIRS manipulation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update snapd to version 2.45.1ubuntu0.2 (Ubuntu), 2.45.1+18.04.2 (18.04), or 2.45.1+20.04.2 (20.04) to remediate the vulnerability.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $910
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-11934 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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