An incorrect handling of a special element in Busybox's ash applet leads to denial of service when processing a crafted shell command, due to the shell mistaking specific characters for reserved characters. This may be used for DoS under rare conditions of filtered command input.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-42375
• https://jfrog.com/blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6T2TURBYYJGBMQTTN2DSOAIQGP7WCPGV/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UQXGOGWBIYWOIVXJVRKHZR34UMEHQBXS/
• https://security.netapp.com/advisory/ntap-20211223-0002/
• https://claroty.com/team82/research/unboxing-busybox-14-vulnerabilities-uncovered-by-claroty-jfrog