SafariWeb browser · Apple
CVE-2010-3821
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 · uneditedWebKit in Apple Safari before 5.0.3 on Mac OS X 10.5 through 10.6 and Windows, and before 4.1.3 on Mac OS X 10.4, does not properly handle the :first-letter pseudo-element in a Cascading Style Sheets (CSS) token sequence, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted web site.
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 analysisThe program reads or writes outside the bounds of an allocated buffer, corrupting adjacent memory. With crafted input an attacker can overwrite control data and, with effort, redirect execution to their own code. Remediation ranges from bounds checking and safe library functions to compiler mitigations, usually alongside a careful audit of the surrounding code.
General guidance for the memory buffer bounds error class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
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
SafariWeb browser
<= 5.0.2= 5.0= 5.0.1<= 4.1.2= 1.0= 1.0.0= 1.0.0b1= 1.0.0b2= 1.0.1= 1.0.2= 1.0.3= 1.1all versionsCVSS 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
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:M/Au:N/C:C/I:C/A:C
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 · scopedSafari 5.0.3 (or later) for Mac OS X 10.5-10.6 and Windows; Safari 4.1.3 (or later) for Mac OS X 10.4
- Open Safari and navigate to Safari > About Safari to check the current version
- For Mac OS X 10.5-10.6 or Windows users: Upgrade to Safari 5.0.3 or later by using Software Update (Mac) or downloading from apple.com/safari (Windows)
- For Mac OS X 10.4 users: Upgrade to Safari 4.1.3 or later via Software Update
- After upgrading, verify the version in Safari > About Safari matches the fixed release
- Ensure JavaScript is enabled in Safari preferences to allow the security update to fully protect against the vulnerability
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2010-3821 — 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-2010-3821 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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