CVE-2020-6113: 
Nitro Pro vulnerability analysis and mitigation

An exploitable vulnerability was discovered in Nitro Pro PDF reader versions 13.13.2.242 and 13.16.2.300, identified as CVE-2020-6113. The vulnerability exists in the object stream parsing functionality when updating the cross-reference table. The issue was discovered by Cisco Talos and publicly disclosed on September 15, 2020, after being patched by the vendor on July 27, 2020 (Talos Report).

The vulnerability occurs during the processing of object streams in PDF documents. When calculating memory allocation for indirect objects list, an integer overflow can occur due to improper size calculation. The application performs a calculation that adds 1 to a value and multiplies it by 0x10 (16) without overflow checks, which can result in an undersized buffer allocation. The vulnerability has been assigned a CVSSv3 score of 8.8 (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) and is classified as CWE-190 (Integer Overflow or Wraparound) (Talos Report).

When exploited, this vulnerability can lead to memory corruption and potential code execution under the context of the application. The high CVSS score of 8.8 indicates severe potential impact, with possible compromise of confidentiality, integrity, and availability of the system (Talos Report).

The vulnerability can be triggered by delivering a specially crafted PDF document to a victim. The attack requires user interaction (opening the malicious PDF) but no privileges, making it relatively straightforward to exploit. The proof-of-concept demonstrates that setting relevant fields to cause a zero-sized buffer allocation results in out-of-bounds writes when setting header fields (Talos Report).

The vulnerability was patched by the vendor on July 27, 2020. Users should upgrade to a version newer than 13.16.2.300 to mitigate this vulnerability (Talos Report).