EUVD-2026-81296
GHSA-v554-hhrr-96v5
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-reachable, low-complexity, unauthenticated parser on default path (AV:N/AC:L/PR:N/UI:N); pure event-loop exhaustion gives A:H with C:N/I:N and no scope change.
Primary rating from Vendor (vulncheck).
CVSS VectorVendor: vulncheck
Lifecycle Timeline
4DescriptionCVE.org
Nodemailer before 9.1.0 contains a quadratic time complexity vulnerability in the addressparser component that allows remote attackers to cause denial of service by supplying a crafted comma-separated address list. Attackers can send a single email with a large number of addresses to block the Node.js event loop for extended periods, consuming 100% CPU and freezing the process.
Articles & Coverage 1
AnalysisAI
Denial of service in Nodemailer before 9.1.0 allows remote, unauthenticated attackers to stall a Node.js process by supplying a crafted comma-separated address list - a single To, Cc, Bcc, From or Reply-To value, or any string fed to the exported addressparser - that triggers quadratic (O(n²)) parsing and blocks the single-threaded event loop at 100% CPU. The issue requires no special library configuration and no cooperating receiver: an approximately 1.5 MB address value freezes the process for roughly 25-30 seconds, and cost scales with the square of input size, so multi-megabyte values can stall a server for minutes. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | No special Nodemailer configuration is required - the quadratic parsing is on the library's default code path and triggers on any To/Cc/Bcc/From/Reply-To value or any string passed to the exported addressparser. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a genuine, credible denial-of-service issue but not a top-tier incident-response priority absent active exploitation. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patch: upgrade nodemailer to version 9.1.0 or later, which fixes the quadratic accumulator in lib/addressparser/index.js and adds the cross-header recipient deduplication in lib/mime-node/index.js; the fix is carried by PR https://github.com/nodemailer/nodemailer/pull/1848 and commits 34da64282dcdc9b0581c721a27ab2fa226673150, 7cc38af, 83b8c48 and 9116da9, with details in https://github.com/nodemailer/nodemailer/security/advisories/GHSA-2x7j-588g-ccc2. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all applications using Nodemailer and identify any version before 9.1.0; immediately enforce a strict maximum length (e.g., 1,000 characters) on every email address field and any string passed to the addressparser, and block or truncate externally supplied comma-separated lists. …
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Same weakness CWE-400 – Uncontrolled Resource Consumption
View allSame technique Denial Of Service
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External POC / Exploit Code
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