Variant weakness
Incomplete
The product receives data from an upstream component, but does not filter all instances of a special element before sending it to a downstream component.
Last updated
Incomplete filtering of this nature may be applied to: sequential elements (special elements that appear next to each other) or non-sequential elements (special elements that appear multiple times in different locations).
4 recorded CVEs are caused by CWE-794 (Incomplete Filtering of Multiple Instances of Special Elements). The highest-severity and most recent are shown first. 1 new CWE-794 CVE has been recorded so far in 2026.
What can happen when CWE-794 is exploited.
Unexpected State
Affects: Integrity
Typically introduced during these phases of the software lifecycle.
MITRE examples of the weakness in code.
The following code takes untrusted input and uses a regular expression to filter "../" from the input. It then appends this result to the /home/user/ directory and attempts to read the file in the final resulting path.
Vulnerable example
my $Username = GetUntrustedInput();Attack input
../../../etc/passwdResulting query
../../etc/passwdResulting query
/home/user/../../etc/passwdCommon questions about CWE-794.
Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.
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