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CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

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394,002

Total vulnerabilities in the database

Nodemailer: Quadratic backtracking in the addressparser free-text fallback allows remote denial of service — nodemailer

Summary

When addressparser finds no address by its strict reading, it falls back to pulling one out of the free text with /\s*\b[^@\s]+@[^\s]+\b\s*/. That pattern backtracks quadratically: [^@\s]+ is retried from every offset and rescans the run to the next @ each time. A single header value holding a long whitespace-free run with no usable @ blocks the Node.js event loop for tens of seconds.

It is cheaper to exploit than GHSA-prgh-xp8r-p3m5: 273KB is enough for ~43s, where the comment-joined shape needed ~1.5MB for ~10s.

Details

The fallback in src/addressparser/index.ts ran the pattern as a search. [^@\s]+ crosses neither whitespace nor @, so from each start offset it scans forward to the next @ or to the end of the run and then fails, and the engine simply advances one character and repeats. Three shapes make every offset fail:

the run holds no @ at all
the only @ has nothing after it
the only @ has nothing before it

A fourth reaches it with a valid address present but placed past a long run, so the long run is walked before the match is found.

PoC

const addressparser = require(&#039;nodemailer/lib/addressparser&#039;);
const s = Date.now();
addressparser(&#039; &gt;&#039; + &#039;&gt;[x][x]&#039;.repeat(40000)); // 273KB
console.log(Date.now() - s, &#039;ms&#039;); // ~43000 ms, blocking

Measured on 10.0.5:

| Value | Parse time | | --- | --- | | '[x]'.repeat(40000) (117KB) | 9.0 s | | '[x]'.repeat(40000) + '@' (117KB) | 8.9 s | | '@' + '[x]'.repeat(40000) (117KB) | 8.8 s | | ' >' + '>[x][x]'.repeat(40000) (273KB) | 42.9 s |

Impact

Algorithmic-complexity denial of service. Node is single threaded, so the block stalls the whole process. Reachable without authentication anywhere inbound header values are handed to this parser, mailparser being the notable case, and reachable from application input wherever a user-supplied string is used as a message address, since mime-node parses to, from and cc when composing.

Patch

The search is replaced by a single linear pass that finds the one offset the pattern can match at, which is then applied there with a sticky regex. Match results are unchanged, verified against the previous implementation over 3.4 million random strings comparing both the match offset and the matched text, plus 800k full-parse comparisons.

Found while validating the report in GHSA-prgh-xp8r-p3m5, not reported externally.

Published: Sep 29, 2026
Updated: Sep 30, 2026
GHSA: GHSA-v53p-9fqp-m79j
Severity: High
Exploit:
CISA KEV:

CVSS v3:

Severity: High
Score: 7.5
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWEs:

Affected Software
References

Software	Affected versions
nodemailer	`< 10.0.6`

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.