CVE-2019-18276
HighCVSS 7.8Exploitation Probability (EPSS)
High risk85th percentile - higher than 85% of all known CVEs
Summary
An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges.
Risk Assessment
An attacker with command execution in the shell can escalate privileges.
Recommendation
Update GNU Bash to a patched version.
Other vulnerabilities in GNU Bash
See all- CVE-2014-7187High
Off-by-one error in the read_token_word function in parse.y in GNU Bash through 4.3 bash43-026 allows remote attackers to cause a denial of service (out-of-bounds array access and application crash) or possibly have unspecified other impact via deeply nested for loops.
- CVE-2014-7186High
The redirection implementation in parse.y in GNU Bash through 4.3 bash43-026 allows remote attackers to cause a denial of service (out-of-bounds array access and application crash) or possibly have unspecified other impact via crafted use of here documents.
- CVE-2014-6277High
GNU Bash through 4.3 bash43-026 does not properly parse function definitions in the values of environment variables, allowing remote attackers to execute arbitrary code or cause a denial of service via a crafted environment.
Original NVD description (English source)
An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges. However, binaries running with an effective UID of 0 are unaffected.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS