FirefoxWeb browser · Mozilla
CVE-2015-0826
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 · uneditedThe nsTransformedTextRun::SetCapitalization function in Mozilla Firefox before 36.0 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read of heap memory) via a crafted Cascading Style Sheets (CSS) token sequence that triggers a restyle or reflow operation.
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 confidenceA heap-based out-of-bounds read vulnerability exists in Mozilla Firefox versions before 36.0 within the nsTransformedTextRun::SetCapitalization function used for CSS text transformation rendering. Attackers can trigger this by tricking users into visiting webpages containing specially crafted CSS token sequences that cause restyle or reflow operations, potentially leading to arbitrary code execution or denial of service.
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
<= 35.0.1= 0.1= 0.2= 0.3= 0.4= 0.5= 0.6= 0.6.1= 0.7= 0.7.1= 0.8= 0.9
Ubuntu LinuxOperating system
= 12.04= 14.04= 14.10= 13.1= 13.2CVSS 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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/Au:N/C:P/I:P/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Identify Firefox installationRun 'firefox --version' from terminal, or check for /usr/bin/firefox, or query package manager (dpkg -l firefox on Debian/Ubuntu, rpm -q firefox on openSUSE)Affected if Firefox is not found on the system
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Check installed Firefox versionExecute 'firefox --version' or use package manager query to retrieve the exact version numberAffected if Version is 35.0.1 or lower, or any version in the 0.x range (0.1 through 0.9) listed in affected versions
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Verify CSS rendering is enabledThe vulnerability is triggered during CSS text transformation rendering in the browser. Ensure web browsing capability exists and is not fully disabled.Affected if Firefox can render web content with CSS styling
The environment is affected if Firefox version 36.0 or newer is not installed, since all earlier versions contain the vulnerable nsTransformedTextRun::SetCapitalization function.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade to Mozilla Firefox version 36.0 or later to remediate this vulnerability. Organizations should deploy the updated browser version through their standard patch management processes and verify successful installation across affected endpoints.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-0826 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-0826 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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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