How severe is GHSA-fv2f-rw9f-v9cm?

No CVSS score has been assigned to GHSA-fv2f-rw9f-v9cm yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-fv2f-rw9f-v9cm?

GHSA-fv2f-rw9f-v9cm affects the following packages: smtp-server (npm). Ecosystems affected: npm.

How do I fix GHSA-fv2f-rw9f-v9cm?

Update smtp-server to 3.18.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fv2f-rw9f-v9cm is resolved across your whole dependency graph.

How do I detect GHSA-fv2f-rw9f-v9cm in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for smtp-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-fv2f-rw9f-v9cm if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is GHSA-fv2f-rw9f-v9cm actively exploited in the wild?

No public exploit code has been indexed for GHSA-fv2f-rw9f-v9cm yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-fv2f-rw9f-v9cm?

GHSA-fv2f-rw9f-v9cm has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 48th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-fv2f-rw9f-v9cm?

GHSA-fv2f-rw9f-v9cm is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-fv2f-rw9f-v9cm published, and has it been updated?

GHSA-fv2f-rw9f-v9cm was published on May 15, 2026 and was last updated on June 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

GHSA-fv2f-rw9f-v9cm: smtp-server

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for GHSA-fv2f-rw9f-v9cm.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs48th percentile — riskier than 48% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

207other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

smtp-servernpm

1.1Mdownloads / week

Description

smtp-server prior to v3.18.3 are vulnerable to unauthenticated memory exhaustion denial-of-service. smtp-server's command parser allows any remote client to consume server memory by sending data without newline characters. The server's _remainder buffer in SMTPStream._write grows without limit, leading to heap exhaustion, prolonged GC pauses that freeze the event loop, and in some cases, process crash.

The _write method in lib/smtp-stream.js appends incoming TCP chunks to this._remainder in command mode. The buffer is only emptied when a newline is found. If a client never sends a newline, the _remainder value will grow indefinitely, causing excess memory consumption.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`smtp-server`	all versions	3.18.3`npm install smtp-server@3.18.3`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for smtp-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update smtp-server to 3.18.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fv2f-rw9f-v9cm is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

smtp-server prior to v3.18.3 are vulnerable to unauthenticated memory exhaustion denial-of-service. smtp-server's command parser allows any remote client to consume server memory by sending data without newline characters. The server's `_remainder` buffer in `SMTPStream._write` grows without limit, leading to heap exhaustion, prolonged GC pauses that freeze the event loop, and in some cases, process crash. The `_write` method in `lib/smtp-stream.js` appends incoming TCP chunks to `this._remainder` in command mode. The buffer is only emptied when a newline is found. If a client never sends a n

O3 Security · Impact-Aware SCA

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smtp-server's command parser memory exhaustion denial-of-serviceGHSA-fv2f-rw9f-v9cm