CVE Vulnerabilities


Out-of-bounds Read

Published: Aug 20, 2021 | Modified: Aug 31, 2021
CVSS 3.x
CVSS 2.x
8.8 HIGH

Acrobat Reader DC versions 2021.005.20054 (and earlier), 2020.004.30005 (and earlier) and 2017.011.30197 (and earlier) are affected by an out-of-bounds read vulnerability. An unauthenticated attacker could leverage this vulnerability achieve arbitrary read / write system information in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.


The software reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Name Vendor Start Version End Version
Acrobat_dc Adobe 15.008.20082 21.005.20054
Acrobat_dc Adobe 17.011.30059 17.011.30197
Acrobat_dc Adobe 20.001.30005 20.004.30005
Acrobat_reader_dc Adobe 15.008.20082 21.005.20054
Acrobat_reader_dc Adobe 17.011.30059 17.011.30197
Acrobat_reader_dc Adobe 20.001.30005 20.004.30005

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.