JenkinsApplication
CVE-2020-2100
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 · uneditedJenkins 2.218 and earlier, LTS 2.204.1 and earlier was vulnerable to a UDP amplification reflection denial of service attack on port 33848.
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 confidenceJenkins versions 2.218 and earlier, LTS 2.204.1 and earlier expose a UDP service on port 33848 that can be exploited for amplification reflection denial of service attacks, allowing attackers to reflect amplified traffic toward victims.
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
JenkinsApplication
<= 2.204.1<= 2.218CVSS 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
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/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.
-
Identify the Jenkins versionRun 'java -jar jenkins.war --version' or check the version displayed in the Jenkins web UI dashboard footer, or check the 'jenkins.war' file version on diskAffected if Version is 2.204.1 or earlier, or between 2.205 and 2.218 inclusive (LTS versions 2.204.1 and earlier are affected; all versions 2.218 and earlier are affected)
-
Verify UDP port 33848 is listeningRun 'netstat -anu | grep 33848' or 'ss -uan | grep 33848' on Linux, or 'netstat -an | grep 33848' on Windows to check if the UDP port is boundAffected if UDP port 33848 is shown as listening or in state LISTENING, indicating the vulnerable UDP service is active
-
Confirm UDP port is externally reachableCheck firewall rules with 'iptables -L -n' or 'ufw status' on Linux, or Windows Firewall inbound rules. Attempt a test packet to port 33848 from an external system using 'nc -u <target> 33848'Affected if Firewall allows inbound UDP traffic on port 33848, meaning the amplification reflection vector can be exploited by external attackers
-
Identify the UDP service bindingRun 'lsof -i :33848' or 'ss -lunp | grep 33848' to identify which process owns the UDP listenerAffected if The process is Jenkins (java process running Jenkins) and it is binding to UDP port 33848
You are affected if running Jenkins version 2.204.1 or earlier (or any version up to 2.218) AND UDP port 33848 is open and reachable on your network, enabling attackers to reflect amplified traffic through your Jenkins server toward victims.
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 Jenkins 2.219 or LTS 2.204.2 or later to patch the vulnerability, or block UDP port 33848 at the network perimeter if immediate upgrade is not feasible.
Fix this in Jenkins
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 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 $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-2100 — 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-2020-2100 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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