Security readout for executives and security teams
Plain-English summary
A crafted PDF could appear to keep its original certification while its contents have been changed. The business risk is trust abuse: employees may rely on a certified document that no longer reflects what was approved. The victim must open the tampered file.
Executive priority
Treat as high priority where certified PDFs influence approvals, contracts, invoices, or compliance decisions. The issue undermines document trust rather than system availability.
Technical view
CVE-2021-28545 is a CWE-353 missing integrity-check issue in Adobe Acrobat Reader DC. A remote unauthenticated attacker can manipulate data in a certified PDF without invalidating the original certification. CVSS 3.1 is 8.1, with network attack vector and required user interaction.
Likely exposure
Exposure is likely where Adobe Acrobat Reader DC is at or below 2020.013.20074, 2020.001.30018, or 2017.011.30188, especially for users handling externally supplied certified PDFs.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires social delivery of a tampered certified PDF and user interaction to open it.
Researcher notes
The bundle identifies affected version ceilings and impact, but does not include fixed build numbers or proof of exploitation. Avoid assuming broader Adobe products are affected beyond Acrobat Reader DC.
Mitigation direction
- Review Adobe APSB21-09 for vendor remediation guidance.
- Update affected Acrobat Reader DC installations to a supported fixed release.
- Prioritize users who handle legal, finance, procurement, or signed PDF workflows.
- Use document-source controls for externally supplied certified PDFs.
Validation and detection
- Inventory Acrobat Reader DC versions across endpoints.
- Flag versions at or below the affected builds listed in CVE data.
- Confirm Adobe update status against APSB21-09 guidance.
- Review mail and document workflows for certified PDF handling exposure.
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-353: 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-2021-28545 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
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:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N2.85.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://helpx.adobe.com/security/products/acrobat/apsb21-09.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.
Missing Support for Integrity Check
Missing Support for Integrity Check represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.