Security readout for executives and security teams
Plain-English summary
CVE-2021-40647 affects man2html 1.6g when it reads a specially crafted string from a file. The reported impact ranges from a crash to arbitrary memory write on systems using GLIBC before 2.29. Public metadata does not provide CVSS, broad affected-product data, or a confirmed fix.
Executive priority
Treat this as a focused exposure review, not an emergency based on current evidence. The potential memory-write impact is serious, but public data is sparse and no active exploitation is cited. Prioritize internet-facing or automated document-processing workflows first.
Technical view
The source description reports heap top-chunk size corruption while man2html 1.6g parses file input. Misalignment can cause segmentation abort. With GLIBC versions before 2.29 and correct alignment, the condition may allow arbitrary write in the program memory space. No CWE, CVSS vector, or vendor advisory is provided in the bundle.
Likely exposure
Exposure appears limited to environments running man2html 1.6g, especially where it processes untrusted or externally supplied manpage-like files. The bundle lists affected vendor and product as n/a, so distribution packaging and downstream exposure require local confirmation.
Exploitation context
The source bundle does not show KEV listing or active exploitation evidence. The provided description indicates a crafted input file can trigger memory corruption, but it does not establish remote reachability, real-world exploitation, or a complete exploitation path.
Researcher notes
Key uncertainties are affected downstream packages, exploitability outside specific GLIBC conditions, and fix availability. The public record identifies man2html 1.6g and GLIBC pre-2.29 relevance, but lacks CVSS, CWE mapping, and detailed vendor remediation guidance.
Mitigation direction
- Inventory systems and packages for man2html 1.6g.
- Check vendor or distribution advisories for patched builds or replacement guidance.
- Avoid processing untrusted files with affected man2html deployments.
- Run any required processing in a constrained, least-privilege environment.
- Prioritize systems using GLIBC earlier than 2.29 for review.
Validation and detection
- Confirm whether man2html is installed and record its exact version.
- Identify workflows where man2html processes user-controlled or third-party files.
- Check GLIBC version on hosts running man2html.
- Review crash logs for unexplained man2html segmentation aborts.
- Verify whether your distribution has backported a fix.
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-2021-40647 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://gist.github.com/untaman/cb58123fe89fc65e3984165db5d40933CVE 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.