CVE-2026-9277 — shell-quote `quote()` does not validate object-token shapes, allowing command injection via line terminators in `.op`

Description (CNA)

shell-quote's `quote()` function did not validate object-token inputs against the operator model used by `parse()`. The `.op` field was backslash-escaped character by character using `/(.)/g`, which in JavaScript does not match line terminators (\n, \r, U+2028, U+2029). A line terminator in `.op` therefore passed through unescaped into the output; POSIX shells treat a literal newline as a command separator, so any content after it would execute as a second command. The vulnerable code path is reachable in two ways: (1) direct construction of `{ op: '...\n...' }` from external input, and (2) via `parse(cmd, envFn)` when `envFn` returns object tokens whose `.op` is attacker-influenced. Both are documented API surface. Fixed by replacing the per-character escape with strict shape validation: `.op` must match the parser's control-operator allowlist; `{ op: 'glob', pattern }` validates `pattern` and forbids line terminators; `{ comment }` validates `comment` and forbids line terminators; any other object shape throws `TypeError`.

Affected (CNA)

Vendor / product	Versions
Not supplied / shell-quote	affected 1.1.0 before 1.8.4

CWE

CWE-78, CWE-77

References

ADP enrichment

CISA-ADP

No English description supplied.

https://github.com/ljharb/shell-quote/security/advisories/GHSA-w7jw-789q-3m8p

CVE

No English description supplied.

http://www.openwall.com/lists/oss-security/2026/05/23/2

redhat-SADP

A flaw was found in the shell-quote component. The quote() function did not properly validate object-token inputs, allowing line terminators to pass unescaped into the output. A remote attacker could exploit this vulnerability by providing specially crafted input, which a POSIX shell would interpret as a command separator. This could lead to command injection, enabling the attacker to execute arbitrary code on the system.