Security readout for executives and security teams
Plain-English summary
CVE-2021-43308 is a denial-of-service issue in the npm package markdown-link-extractor. If an application lets attackers submit text that this package parses, crafted input can make processing take excessive time and degrade availability.
Executive priority
Treat as a targeted availability risk, not a data-theft issue. Prioritize internet-facing services that parse user-submitted Markdown and have weak request limits.
Technical view
The issue is CWE-1333: an inefficient regular expression with exponential behavior in the package's exported function. The CVSS vector is network-reachable, unauthenticated, high complexity, no confidentiality or integrity impact, and high availability impact.
Likely exposure
Exposure is likely limited to Node.js applications that use markdown-link-extractor directly or transitively and pass attacker-controlled Markdown or text into its exported function.
Exploitation context
The bundle does not show KEV listing or other evidence of active exploitation. Successful abuse requires arbitrary input reaching the vulnerable parser and is rated high complexity.
Researcher notes
Affected versions and a fixed version are not specified in the supplied bundle. Validation should focus on dependency reachability, attacker-controlled input paths, and operational blast radius.
Mitigation direction
- Inventory direct and transitive use of markdown-link-extractor.
- Check maintainer or JFrog guidance for affected and fixed versions.
- Avoid sending untrusted large Markdown input to this parser.
- Apply request size, timeout, and worker isolation controls around Markdown processing.
- Replace or remove the dependency if no maintained fix is available.
Validation and detection
- Search dependency manifests and lockfiles for markdown-link-extractor.
- Identify application paths that parse user-supplied Markdown or text.
- Confirm deployed package versions against vendor or advisory guidance.
- Review availability monitoring for parser-related latency or resource spikes.
- Add regression coverage for bounded processing of malformed Markdown input.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-1333: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-43308 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H2.23.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.9MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://research.jfrog.com/vulnerabilities/markdown-link-extractor-redos-xray-211350/CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Inefficient Regular Expression Complexity
Inefficient Regular Expression Complexity represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.