Security readout for executives and security teams
Plain-English summary
CVE-2021-26605 affects Unidocs ezPDFReader versions 2.0 through 3.0. A vulnerable service can accept crafted JSON-RPC input that the ezPDF launcher executes, allowing unauthorized command execution. The public bundle rates this high severity, but does not provide evidence of active exploitation.
Executive priority
Treat this as a high-priority exposure if ezPDFReader 2.0 to 3.0 exists in the environment. The issue can affect integrity without authentication or user interaction, but the provided sources do not prove exploitation in the wild.
Technical view
The flaw is improper input validation, mapped to CWE-20, in ezPDFReader service handling of JSON-RPC communication. The launcher receives crafted input values and executes them. CVSS 3.1 is 7.5, with network attack vector, low complexity, no privileges, and no user interaction required.
Likely exposure
Exposure is most likely on systems running Unidocs ezPDFReader 2.0 to 3.0, especially where the related service or JSON-RPC interface is reachable from untrusted networks. The source bundle provides no CPEs and no deployment-specific indicators.
Exploitation context
The CVE record describes unauthenticated network-reachable command execution conditions. CISA KEV status is false in the bundle, and no cited source confirms active exploitation. Public details in the bundle are limited and do not include exploit maturity or observed campaigns.
Researcher notes
Key constraints are the narrow version range and limited public detail. The bundle names improper input validation in JSON-RPC handling but does not identify a fixed release, workaround, CPE, proof of concept, or exploit activity. Validate exposure through product inventory and service reachability.
Mitigation direction
- Inventory ezPDFReader installations and identify versions 2.0 through 3.0.
- Check Unidocs or KRCERT guidance for fixed versions or official mitigation.
- Upgrade, remove, or isolate affected ezPDFReader deployments according to vendor guidance.
- Restrict access to the ezPDFReader service and JSON-RPC interface where possible.
- Monitor affected hosts for unexpected launcher activity or configuration changes.
Validation and detection
- Confirm installed ezPDFReader versions on managed endpoints and servers.
- Determine whether the ezPDFReader service is running on affected systems.
- Review whether JSON-RPC communication is reachable from untrusted networks.
- Verify compensating access controls around affected hosts and services.
- Check logs for unexpected ezPDF launcher execution patterns.
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-20: 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-2021-26605 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
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:N/S:U/C:N/I:H/A:N3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.boho.or.kr/krcert/secNoticeView.do?bulletin_writing_sequence=36168CVE 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.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.