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FirefoxWeb browser · Mozilla

CVE-2022-31744

MEDIUM · 6.5 CVSS v3.1 Published 2022-12-22
Fix available
A fix is available. Upgrade to 91.11 / 101.0 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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
An attacker could have injected CSS into stylesheets accessible via internal URIs, such as resource:, and in doing so bypass a page's Content Security Policy. This vulnerability affects Firefox ESR < 91.11, Thunderbird < 102, Thunderbird < 91.11, and Firefox < 101.

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

A CSS injection vulnerability in Firefox and Thunderbird allows attackers to inject malicious CSS into stylesheets accessed via internal URI schemes (such as resource:), thereby bypassing the page's Content Security Policy. This could enable data exfiltration or other CSP-prevented attacks.

MitigationUpgrade to Firefox ESR 91.11+, Thunderbird 91.11+/102+, or Firefox 101+ to resolve the CSS injection and CSP bypass 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
FirefoxWeb browser
Affected:< 101.0
Firefox EsrWeb browser
Affected:< 91.11
ThunderbirdApplication
Affected:< 91.11

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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/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. Identify the installed Mozilla product
    Open Firefox or Thunderbird and go to Help > About [Product Name]. The version will be displayed in the window that opens.
    Affected if The product is Mozilla Firefox or Mozilla Thunderbird
  2. Confirm the exact version number
    Note the full version number shown in the About window (for example, 100.0 or 91.10). For Firefox, also determine if it is the ESR release by checking the version string for 'ESR'.
    Affected if The version displayed is below 101.0 for Firefox, below 91.11 for Firefox ESR, or below 91.11 for Thunderbird
  3. Verify CSS access to internal URI schemes is possible
    Check if the browser or mail client can load stylesheets from internal URI schemes such as resource:, chrome:, or about:. This is a default behavior in both products and requires no special configuration.
    Affected if The installed version is vulnerable AND the client can access stylesheets via internal URI schemes (default enabled)

A user is affected if they run Firefox below version 101.0, Firefox ESR below version 91.11, or Thunderbird below version 91.11, and the browser loads stylesheets from internal URI schemes (resource:, chrome:, about:), which is default behavior.

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.

dbcve · scoped
Upgrade available Upgrade to 91.11 / 101.0 or later
Fixed in 91.11101.0
Interim mitigation

Upgrade to Firefox ESR 91.11+, Thunderbird 91.11+/102+, or Firefox 101+ to resolve the CSS injection and CSP bypass vulnerability.

Recommended fix High confidence

Firefox 101.0, Firefox ESR 91.11, Thunderbird 91.11

  1. 1. Open Firefox, Firefox ESR, or Thunderbird
  2. 2. Navigate to Menu > Help > About (or go to about:support in the URL bar)
  3. 3. Click 'Check for Updates' to download and install the latest version
  4. 4. Restart the application after the update completes
  5. 5. Verify the version by returning to Menu > Help > About - it should show version 101.0 for Firefox, 91.11 for Firefox ESR, or 91.11 for Thunderbird

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

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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-2022-31744 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
  • No spam, self-promotion, credentials, or personal data