CWE-77: Improper Neutralization of Special Elements used in a Command
Sources read 2026-10-29. MITRE's own page · All weakness notes · Added to CISA's list in the last seven days
What it is
From MITRE's CWE catalogue
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
MITRE classes it as a class-level weakness and rates the likelihood of exploit as high.
What it lets an attacker do
From MITRE's CWE catalogue
- Execute Unauthorized Code or Commands (affects: integrity, confidentiality, availability)
On CISA's exploited list
From CISA's exploited list
4 of the 108 entries CISA added from 2026-08-02 to 2026-10-30 name CWE-77, against 1 of 69 in the 90 days before. Over the whole catalogue 33 entries name it. The counts are small, so read them as a rough order, not a rate.
CISA's list is not every flaw that is exploited: it holds the ones CISA has evidence of, listed on the day it added them.
- CVE-2026-105134, Ahsay AhsayCBS, added 2026-10-14
- CVE-2026-96951, Microsoft Windows, added 2026-10-13
- CVE-2016-3081, Apache Struts, added 2026-10-08
- CVE-2026-8037, Progress LoadMaster, added 2026-08-07
- CVE-2026-42271, BerriAI LiteLLM, added 2026-06-08
How MITRE says to find it
From MITRE's CWE catalogue
- Automated Static Analysis
What MITRE suggests
From MITRE's CWE catalogue
These are MITRE's suggestions, quoted as it gives them. They are not a complete fix and not a substitute for reading the vendor's advisory for the product you run.
- Architecture and Design: If at all possible, use library calls rather than external processes to recreate the desired functionality.
- Implementation: If possible, ensure that all external commands called from the program are statically created.
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- Operation: Run time: Run time policy enforcement may be used in an allowlist fashion to prevent use of any non-sanctioned commands.
Attack patterns MITRE links to it
From MITRE's CWE catalogue
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