CVE-2026-102422: shell-quote: `quote()` command injection via a line terminator in a token after a `{ comment }` token

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.4%, percentile 31: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 31% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes shell-quote (npm) >= 1.8.4, < 1.11.0, fixed in 1.11.0. Check your lockfile, including transitive dependencies.

What it is

shell-quote's quote() function emits a { comment } token as # followed by its text, which comments out the rest of the shell line, including the opening quote of any later string token. A line terminator (\n, \r, U+2028, U+2029) in that later string therefore ends the comment, and the rest of the string is parsed as shell input: quote(['echo', 'ok', { comment: 'x' }, 'a\nid;#']) runs id in sh, bash, dash, ksh and zsh. parse() emits a comment token for a # in the middle of a word (for example http://example.com/#frag), so callers that combine parse() output with another untrusted string, such as quote(parse(untrustedCommand).concat(untrustedArg)), are affected. The fix for CVE-2026-9277 rejected line terminators in the comment's own text, but not in the tokens after it. Fixed in 1.11.0: quote() throws a TypeError when a string after a { comment } token contains a line terminator.

From the GitHub advisory

Impact

quote() emits a { comment } token as # followed by its text, which comments out the rest of the shell line, including the opening quote of any later string token. A line terminator in that later string ends the comment, and the rest of the string is parsed as shell input:

Passed to sh, bash, dash, ksh, or zsh, this runs id.

parse() emits a comment token for a # in the middle of a word (for example http://example.com/#frag), so callers that combine parse() output with another untrusted string, such as quote(parse(untrustedCommand).concat(untrustedArg)), are affected. The fix for CVE-2026-9277 rejected line terminators in the comment's own text, but not in the tokens after it.

Exploitation requires an attacker-controlled string containing a line terminator that follows a { comment } token in the same quote() call.

Weakness type: CWE-78.

Product: shell-quote (npm) · Assigned by: harborist · Published: 2026-09-29

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.38% probability of exploitation activity in the next 30 days; percentile 31.

Timeline

• 2026-09-29 — CVE record published by harborist
• 2026-09-30 — CVE record last updated
• 2026-10-06 — GitHub-reviewed advisory GHSA-pqg4-j6r4-53mv published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. GHSA-pqg4-j6r4-53mv github.com
2. Fix commit github.com

Vulnerability records

1. GitHub Advisory GHSA-pqg4-j6r4-53mv github.com
2. CVE.org record CVE-2026-102422 cve.org
3. NVD entry CVE-2026-102422 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. npmjs.com npmjs.com

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