Security readout for executives and security teams
Plain-English summary
This Adobe InCopy flaw can let an attacker run code if a user opens a malicious XML file. The impact is serious because the code runs with the user’s permissions, but exploitation requires user interaction and the source bundle does not show known active exploitation.
Executive priority
Treat this as a high-priority endpoint remediation item for teams using InCopy, not an internet-wide emergency. The main business risk is compromise through malicious files sent to users.
Technical view
CVE-2021-39819 is a CWE-788 memory corruption issue in Adobe InCopy 11.1 and earlier caused by insecure handling of malicious XML files. CVSS 3.1 is 7.8 with local attack vector, low complexity, no privileges required, and required user interaction, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on endpoints where Adobe InCopy 11.1 or earlier is installed, especially publishing or content teams that receive XML or document assets from external sources.
Exploitation context
The attacker must convince a user to open a malicious XML file. The source bundle does not identify public exploit activity, and KEV status is false, so active exploitation is not evidenced here.
Researcher notes
Evidence supports arbitrary code execution via malicious XML parsing in InCopy 11.1 and earlier. No exploit details, patch version, or active exploitation evidence are included beyond the Adobe advisory reference and CVE metadata.
Mitigation direction
- Inventory endpoints for Adobe InCopy 11.1 and earlier.
- Apply Adobe guidance from APSB21-71 for affected installations.
- Limit opening XML files from untrusted or unexpected sources.
- Prioritize remediation for users handling external publishing assets.
- Use least-privilege accounts where InCopy is required.
Validation and detection
- Confirm installed Adobe InCopy versions across managed endpoints.
- Compare affected systems against Adobe APSB21-71 guidance.
- Verify remediation through software inventory or endpoint management records.
- Review workflows that accept XML files from outside parties.
- Check security tooling for suspicious activity tied to document handling.
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
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CWE-788: Exact CWE lookup
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Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-39819 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://helpx.adobe.com/security/products/incopy/apsb21-71.htmlCVE 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.
Access of Memory Location After End of Buffer
Access of Memory Location After End of Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.