FirefoxWeb browser · Mozilla
CVE-2023-5758
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 · uneditedWhen opening a page in reader mode, the redirect URL could have caused attacker-controlled script to execute in a reflected Cross-Site Scripting (XSS) attack. This vulnerability affects Firefox for iOS < 119.
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 confidenceThis is a reflected Cross-Site Scripting (XSS) vulnerability in Firefox for iOS versions prior to 119. When a user opens a page in reader mode, the redirect URL mechanism fails to properly sanitize input, allowing an attacker to inject and execute arbitrary JavaScript in the context of the user's browser session through a maliciously crafted URL.
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
< 119.0CVSS 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
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 checksWork through these to decide whether this CVE applies to you.
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Confirm Firefox for iOS is installedLocate the Firefox app on the iOS device home screen or App LibraryAffected if Firefox for iOS app is present on the device
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Determine the installed Firefox for iOS versionOpen the iOS Settings app, scroll down to Firefox, tap on it, and record the version number shownAffected if Version number is displayed and is below 119.0
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Compare version against the affected rangeCheck if the recorded version number is less than 119.0 (for example, 118.x, 118.0.1, etc.)Affected if Installed version is any release prior to 119.0
If Firefox for iOS is installed with a version lower than 119.0, the environment is affected by the reflected XSS vulnerability in reader mode.
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.
dbcve · scoped119.0
Upgrade Firefox for iOS to version 119 or later. Until the update is applied, users should avoid opening untrusted links that trigger reader mode.
Firefox for iOS 119.0 or later
- Open the App Store on your iOS device
- Search for "Firefox" or locate Firefox in your installed apps
- Tap "Update" to install Firefox for iOS version 119.0 or later
- Alternatively, enable automatic app updates in Settings > App Store > Automatic Downloads to ensure future security updates are applied
Generated from the published advisory — verify against the referenced sources before acting.
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-2023-5758 — 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-2023-5758 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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