Security readout for executives and security teams
Plain-English summary
CVE-2020-26311 affects the Node.js useragent parser. A specially crafted user-agent string can make vulnerable regular expressions consume excessive CPU, causing denial of service. The source bundle says all versions were affected at publication and no patch was available then.
Executive priority
Treat as a high-priority availability risk for internet-facing Node.js services using this dependency. Prioritize inventory first, then remove, replace, or contain exposed parsing paths based on business criticality.
Technical view
The issue is CWE-1333 ReDoS in 3rd-Eden useragent. Network-reachable applications that parse attacker-controlled User-Agent headers may spend excessive time evaluating vulnerable regexes, impacting availability. CVSS v4.0 is 8.7 high with network access, low complexity, no privileges, and high availability impact.
Likely exposure
Exposure is most likely in Node.js services using the 3rd-Eden useragent package on public HTTP request paths, analytics ingestion, bot detection, logging enrichment, or middleware that parses untrusted User-Agent strings.
Exploitation context
The bundle does not show CISA KEV listing or cited evidence of active exploitation. The practical risk is unauthenticated remote denial of service where user-agent parsing is reachable with attacker-controlled input.
Researcher notes
Evidence supports ReDoS in useragent and no patch at publication. The bundle’s affected-version metadata is sparse, so verify installed versions and vendor status directly before declaring remediation complete.
Mitigation direction
- Inventory applications and lockfiles for the 3rd-Eden useragent package.
- Check the GitHub advisory and issue for current vendor guidance.
- Avoid parsing untrusted User-Agent strings with this package where feasible.
- Consider replacement or isolation until vendor-supported remediation is available.
- Apply operational controls for abuse: rate limits, CPU monitoring, and request filtering.
Validation and detection
- Search dependency manifests and lockfiles for useragent package usage.
- Trace request paths that pass User-Agent headers into the parser.
- Confirm whether affected parsing is reachable without authentication.
- Review production telemetry for CPU spikes tied to unusual User-Agent values.
- Document compensating controls if removal or replacement is deferred.
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-2020-26311 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
- High
- CVSS
- 8.7 (4.0)
- Known Exploited
- No
- Published
Vector: 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/U:Green
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Green——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
8.7HighVector: 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/U:Green
Source materials
- CVE List V5 sourceCVE List V5
- https://securitylab.github.com/advisories/GHSL-2020-312-redos-useragent/CVE reference
- https://github.com/3rd-Eden/useragent/issues/167CVE reference
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.