Security readout for executives and security teams
Plain-English summary
DjVuLibre could mishandle a specially crafted DjVu document and write outside expected memory. The cited CVE describes crashes and segmentation faults, not confirmed remote code execution. Business urgency is highest where servers, mail gateways, document converters, or user workstations process untrusted DjVu files.
Executive priority
Treat this as a targeted patching item, not an emergency, unless untrusted DjVu files are processed automatically. Prioritize internet-facing document workflows, mail/file ingestion, and shared workstations handling unknown files.
Technical view
CVE-2021-3630 is a CWE-787 out-of-bounds write in DJVU::DjVuTXT::decode() in DjVuText.cpp. The flaw affects DjVuLibre versions before 3.5.28 and is triggered by a crafted DjVu file. Public sources cite crash/segmentation fault impact and Debian/Fedora security updates.
Likely exposure
Exposure is most likely on Linux systems with DjVuLibre or libdjvulibre installed, especially document viewers, thumbnailers, converters, indexing pipelines, upload processing, and email/file-ingestion workflows that parse DjVu content.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The documented trigger is a crafted DjVu file. Evidence supports denial-of-service style impact through crashes; stronger impact is not established in the supplied bundle.
Researcher notes
The source bundle lacks CVSS details and does not prove exploitation in the wild. The affected-version statement should be interpreted from the CVE description: versions before 3.5.28. Distro advisories may backport fixes without changing upstream version strings.
Mitigation direction
- Upgrade DjVuLibre to 3.5.28 or a vendor-patched package.
- Apply Debian or Fedora security updates where applicable.
- Limit DjVu processing for untrusted uploads and attachments.
- Remove DjVuLibre from systems that do not require DjVu support.
- Check vendor guidance for distribution-specific fixed package versions.
Validation and detection
- Inventory hosts and containers for DjVuLibre or libdjvulibre packages.
- Confirm installed versions are 3.5.28 or vendor-patched builds.
- Identify applications that parse DjVu files from users or email.
- Verify document conversion and thumbnail services received patched packages.
- Review vulnerability scanner findings against distro advisory package versions.
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-787: 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-2021-3630 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://bugzilla.redhat.com/show_bug.cgi?id=1977427CVE reference · x_refsource_MISC
- [debian-lts-announce] 20210703 [SECURITY] [DLA 2702-1] djvulibre security updateCVE reference · mailing-list, x_refsource_MLIST
- FEDORA-2021-fd6f2727c8CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-7514c11a37CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-d19172badbCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-6422a16aedCVE reference · vendor-advisory, x_refsource_FEDORA
- DSA-5032CVE reference · vendor-advisory, x_refsource_DEBIAN
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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.