Security readout for executives and security teams
Plain-English summary
CVE-2021-4305 is a denial-of-service weakness in Woorank robots-txt-guard. A crafted pattern can make its regular expression processing inefficient, consuming CPU and reducing availability. The published severity is low because impact is limited to availability and requires adjacent access plus low privileges.
Executive priority
Treat this as a low-priority availability risk unless the library is exposed to untrusted pattern input in a sensitive service. Patch during normal maintenance, but prioritize faster if robots parsing sits on a public or business-critical request path.
Technical view
The issue affects makePathPattern in lib/patterns.js and is classified as CWE-1333, inefficient regular expression complexity. Manipulating the pattern argument can trigger ReDoS behavior. CVSS v3.1 is 3.5 with no confidentiality or integrity impact and low availability impact. A patch commit is identified as c03827cd2f9933619c23894ce7c98401ea824020.
Likely exposure
Exposure is likely limited to applications using Woorank robots-txt-guard where a low-privileged or adjacent actor can influence pattern input. The source bundle does not identify exact affected versions, package ranges, or downstream products.
Exploitation context
The vulnerability entry says exploit details were publicly disclosed and may be used. There is no KEV listing and no provided source confirms active exploitation in the wild.
Researcher notes
Key gaps are version range and real-world package adoption. Focus analysis on how pattern reaches makePathPattern, whether input is attacker-controlled, and whether resource limits contain ReDoS effects. Do not assume active exploitation beyond public disclosure evidence.
Mitigation direction
- Inventory applications using Woorank robots-txt-guard.
- Apply the vendor patch commit or a vendor-confirmed fixed release.
- Avoid passing untrusted pattern values into robots-txt-guard until patched.
- Add timeouts or resource controls around pattern processing where feasible.
- Monitor vendor and repository guidance for affected version details.
Validation and detection
- Check dependency manifests and lockfiles for robots-txt-guard usage.
- Confirm deployed source includes commit c03827cd2f9933619c23894ce7c98401ea824020 or later vendor fix.
- Review call sites for user-controlled pattern input.
- Run regression tests for malformed long patterns without exposing production services.
- Monitor logs and CPU metrics for unusual availability degradation.
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-2021-4305 mapping review
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Open ATT&CK lookup- Severity
- Low
- CVSS
- 3.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
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:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L2.11.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
3.5LowVector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://vuldb.com/?id.217448CVE reference · vdb-entry, technical-description
- https://vuldb.com/?ctiid.217448CVE reference · signature, permissions-required
- https://github.com/Woorank/robots-txt-guard/pull/4CVE reference · exploit, issue-tracking
- https://github.com/Woorank/robots-txt-guard/commit/c03827cd2f9933619c23894ce7c98401ea824020CVE reference · patch
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.