Security readout for executives and security teams
Plain-English summary
CVE-2021-39823 is a high-severity flaw in Adobe SVG Native Viewer. A malicious SVG file could trigger memory corruption and potentially run code as the current user. The attack requires a user to open or process the file, so exposure depends on whether the viewer is installed and handles untrusted SVG content.
Executive priority
Prioritize remediation where employees or automated workflows handle external SVG files. The issue can lead to code execution, but requires user interaction and has no supplied evidence of active exploitation.
Technical view
The issue is a heap buffer overflow, CWE-122, in Adobe SVG Native Viewer version 8182d14dfad5d1e10f53ed830328d7d9a3cfa96d and earlier. CVSS 3.1 is 7.8 with local attack vector, low complexity, no privileges required, required user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Organizations are most exposed where Adobe SVG Native Viewer is installed in design, document, testing, or automation workflows that receive SVG files from external or untrusted sources. The source bundle does not provide CPEs or broad product integration details.
Exploitation context
The CVE record states user interaction is required through a malicious .svg file. The bundle does not include evidence of active exploitation, and it is not listed as KEV. Treat exploit status as unconfirmed from the supplied sources.
Researcher notes
Affected-version detail is limited in the bundle: the CVE names one commit/build and earlier, with unspecified CPEs. Focus validation on confirmed viewer presence, SVG handling paths, and vendor bulletin status rather than assuming exposure through unrelated Adobe products.
Mitigation direction
- Review Adobe APSB21-72 and apply the vendor-recommended update or workaround.
- Inventory systems or workflows using Adobe SVG Native Viewer.
- Restrict opening SVG files from untrusted sources in affected workflows.
- Isolate or remove vulnerable viewer builds until vendor guidance is applied.
Validation and detection
- Confirm whether Adobe SVG Native Viewer is present in the environment.
- Check installed build or commit against 8182d14dfad5d1e10f53ed830328d7d9a3cfa96d and earlier.
- Verify remediation status against Adobe APSB21-72.
- Confirm user-facing workflows do not automatically process untrusted SVG files.
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-122: 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 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-2021-39823 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
- 7.8 (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/svg-native-viewer/apsb21-72.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.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.