Security readout for executives and security teams
Plain-English summary
CVE-2021-40900 describes a denial-of-service risk in regexfn v1.0.5 during email validation. A specially malformed email string can make validation consume excessive processing time. Business impact depends on whether this library is used on public or high-volume input paths.
Executive priority
Treat this as a targeted availability risk. Prioritize validation if regexfn v1.0.5 is present on public-facing forms or APIs. Urgency is lower if the library is absent, internal-only, or shielded by length limits and rate controls.
Technical view
The record identifies a Regular Expression Denial of Service vulnerability in regexfn v1.0.5 when validating crafted invalid emails. No CVSS score, CWE, vendor fix, or affected CPE data is provided in the supplied sources, so exposure must be confirmed by dependency and code-path review.
Likely exposure
Exposure is most likely where regexfn v1.0.5 validates user-supplied email addresses, especially signup, contact, newsletter, or API form inputs. The source bundle does not prove broader product impact.
Exploitation context
The CVE is not listed as KEV in the supplied bundle, and no cited source claims active exploitation. The practical risk is availability degradation if attacker-controlled email input reaches the vulnerable validation path.
Researcher notes
Evidence is thin: the CVE description names regexfn v1.0.5 and crafted invalid emails, but does not include CVSS, CWE, patch status, or exploit observations. Avoid assuming package ecosystem scope beyond the cited regexfn reference.
Mitigation direction
- Inventory applications for regexfn v1.0.5 or bundled copies of its email validation code.
- Check upstream project guidance for a fixed release or recommended replacement.
- Replace vulnerable validation with a maintained library if no supported fix exists.
- Limit email input length before regex validation on exposed routes.
- Apply rate limiting to public forms and APIs accepting email addresses.
Validation and detection
- Review package manifests and lockfiles for regexfn v1.0.5.
- Search application code for regexfn imports or copied email validation regexes.
- Map whether email validation receives unauthenticated or high-volume input.
- Run safe performance regression tests in non-production environments.
- Confirm mitigations do not break legitimate email validation workflows.
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.
CVE-2021-40900 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/yetingli/SaveResults/blob/main/js/regexfn.jsCVE 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.