CVE-2021-20197: broadcom brocade_fabric_operating_system_firmware Link Following

Vulnerability summary

CVE-2021-20197 is a medium (CVSS 6.3) Link Following vulnerability in broadcom brocade_fabric_operating_system_firmware. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.7% of scored vulnerabilities.

Timeline

1. 26-03-2021
   PublishedVulnerability first disclosed.
2. 03-12-2025
   Last modifiedVulnerability information updated.

Description

There is an open race window when writing output in the following utilities in GNU binutils version 2.35 and earlier:ar, objcopy, strip, ranlib. When these utilities are run as a privileged user (presumably as part of a script updating binaries across different users), an unprivileged user can trick these utilities into getting ownership of arbitrary files through a symlink.

• CWE-59Improper Link Resolution Before File Access ('Link Following')The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
• CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.