GNU Bourne-Again Shell (Bash) Arbitrary Code Execution Vulnerability

CheckOps priority index

9.3/10 Patch within 24 h

Severity9.8

Probability10.0

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 100.00% higher than 99.99% of CVEs

CVSS 3.1 9.8 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:

Exploited for 1,740 days 28 Jan 2022

CISA due date 28 Jul 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)28 Jan 2022
Exploited in EUVD (ENISA)28 Jan 2022
Used by ransomwareno
EPSS above 10 %100.00%
No account, over the networkyes

What to do

Fix

Update to a fixed version: 4.3-9.1

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, aka "ShellShock." NOTE: the original fix for this issue was incorrect; CVE-2014-7169 has been assigned to cover the vulnerability that is still present after the incorrect fix.

Affected products

Bourne-Again Shell (Bash)

Weaknesses (CWE)

CWE-78

Open source packages OSV

bashDebian:11 · CVE-2014-6271
fixed in 4.3-9.1
bashDebian:12 · CVE-2014-6271
fixed in 4.3-9.1
bashDebian:13 · CVE-2014-6271
fixed in 4.3-9.1

Timeline

24 Sept 2014
Published
28 Jan 2022
Exploitation reported (ENISA)
28 Jan 2022
Added to the KEV catalog
28 Jul 2022
CISA remediation due date
26 Sept 2026
EPSS peak: 100.00%

Other exploited vulnerabilities from the same vendor

CVE-2026-24061GNU InetUtils Argument Injection Vulnerability
9.3 · Background exploitation
CVE-2014-6278GNU Bash OS Command Injection Vulnerability
8.9 · Background exploitation
CVE-2023-4911GNU C Library Buffer Overflow Vulnerability
6.8 · Background exploitation
CVE-2014-7169GNU Bourne-Again Shell (Bash) Arbitrary Code Execution Vulnerability
9.3 · Background exploitation