FirefoxWeb browser · Mozilla
CVE-2023-5388
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 · uneditedNSS was susceptible to a timing side-channel attack when performing RSA decryption. This attack could potentially allow an attacker to recover the private data. This vulnerability affects Firefox < 124, Firefox ESR < 115.9, and Thunderbird < 115.9.
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 confidenceNSS (Network Security Services) library contained a timing side-channel vulnerability in RSA decryption operations. Attackers could potentially exploit measurable timing variations during decryption to infer private key material or plaintext data over multiple observations.
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
< 115.9.0< 124.0
Debian LinuxOperating system
= 10.0< 115.9.0CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
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 installation and versionOpen Firefox, navigate to Help > About Firefox, or execute 'firefox --version' in command lineAffected if Installed version is below 115.9.0 or below 124.0
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Identify Thunderbird installation and versionOpen Thunderbird, navigate to Help > About Thunderbird, or execute 'thunderbird --version' in command lineAffected if Installed version is below 115.9.0
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Check NSS library version on Debian 10Run 'dpkg -l libnss3' to list the installed NSS library package and versionAffected if System runs Debian 10 with NSS library version matching the vulnerable release
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Confirm RSA decryption is in useInspect SSL/TLS traffic, server logs, or application behavior that involves RSA key exchange or decryption operationsAffected if The system performs RSA decryption operations (this is the default for HTTPS and many other cryptographic protocols)
A system is affected if it runs a vulnerable version of Firefox (below 115.9.0 or below 124.0), Thunderbird (below 115.9.0), or Debian 10 with the vulnerable NSS library, AND performs RSA decryption operations.
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 · scoped115.9.0124.0
Update affected products to Firefox >=124, Firefox ESR >=115.9, or Thunderbird >=115.9, which contain the patched NSS version with constant-time RSA decryption.
Firefox 124.0+ / Firefox ESR 115.9.0+ / Thunderbird 115.9.0+
- For Firefox: Upgrade to version 124.0 or later, or Firefox ESR 115.9.0 or later
- For Thunderbird: Upgrade to version 115.9.0 or later
- For Debian 10: Apply security updates for the libnss3 package via 'apt-get update && apt-get upgrade' or 'apt-get update && apt-get install libnss3'
- Restart the application after updating
- Verify the installed version matches or exceeds the fixed releases
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 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 $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-5388 — 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-2023-5388 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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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.
- 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