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CVE-2021-21086· NVD / CVE Program· CNA adobe

Adobe Reader CoolType Arbitrary Stack Manipulation

Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by an Out-of-bounds Write vulnerability in the CoolType library. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

HighCVSS 7.8 · v3.1—Proof of concept No fix recorded
Published
Sep 2, 2021
Updated
Jun 16, 2026
EPSS
4.7% · 92th percentile
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Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.7%

CNA vs NVD score

NVD
7.8
CNA · adobe
7.8
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
adobeacrobat
adobeacrobat dc
adobeacrobat reader
adobeacrobat reader dc
applemacos
microsoftwindows

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • adobe acrobat17.011.30056 and later · up to 17.011.30188 inclusive
  • adobe acrobat20.001.30005 and later · up to 20.001.30018 inclusive
  • adobe acrobat dc20.006.20042 and later · up to 20.013.20074 inclusive
  • adobe acrobat reader17.011.30059 and later · up to 17.011.30188 inclusive
  • adobe acrobat reader20.001.30005 and later · up to 20.001.300183 inclusive
  • adobe acrobat reader dc20.006.20042 and later · up to 20.013.20074 inclusive

Versions reported by the vendor

Affected version ranges reported by the assigning authority (adobe). Independent of NVD's CPE analysis and usually ahead of it.

  • Adobe Acrobat Reader

    • unspecified and later · up to and including 2020.013.20074affected
    • unspecified and later · up to and including 2020.001.30018affected
    • unspecified and later · up to and including 2017.011.30188affected
    • unspecified and later · up to and including Noneaffected

Same product

adobe: all records

Other highest-scoring records for the same primary product.

  • CVE-2011-2462Unspecified vulnerability in the U3D component in Adobe Reader and Acrobat 10.1.1 and earlier on Windows and Mac OS X, and Adobe Reader 9.x KEV
    96Now
  • CVE-2013-3346Adobe Reader and Acrobat 9.x before 9.5.5, 10.x before 10.1.7, and 11.x before 11.0.03 allow attackers to execute arbitrary code or cause a KEV
    93Now
  • CVE-2021-21017Acrobat Reader DC Heap-based Buffer Overflow Vulnerability Could Lead To Arbitrary Code ExecutionKEV
    91Now
  • CVE-2009-3459Heap-based buffer overflow in Adobe Reader and Acrobat 7.x before 7.1.4, 8.x before 8.1.7, and 9.x before 9.2 allows remote attackers to exeKEV
    91Now
  • CVE-2008-2992Stack-based buffer overflow in Adobe Acrobat and Reader 8.1.2 and earlier allows remote attackers to execute arbitrary code via a PDF file tKEV
    91Now
  • CVE-2009-3953The U3D implementation in Adobe Reader and Acrobat 9.x before 9.3, 8.x before 8.2 on Windows and Mac OS X, and 7.x before 7.1.4 allows remotKEV
    90Now

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:262021-12-02

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+90 d
  3. TodaySep 30, 2026+1854 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records