CVE-2026-9277

Description

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`.

How to fix CVE-2026-9277

To remediate CVE-2026-9277, upgrade the affected package to a fixed version below.

• —upgrade to 1.7.4+~1.7.1-1+deb12u1 or later
• —upgrade to 1.8.4 or later

Is CVE-2026-9277 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 1.7.4+~1.7.1-1+deb12u1
• >= 1.1.0, < 1.8.4

CVSS scores

References (7)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-9277
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-9277
• PATCHgithub.com/ljharb/shell-quote
• WEBgithub.com/ljharb/shell-quote/commit/1518179
• WEB