How severe is CVE-2021-21277?

CVE-2021-21277 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-21277?

CVE-2021-21277 affects the following packages: angular-expressions (npm). Ecosystems affected: npm.

How do I fix CVE-2021-21277?

Update angular-expressions to 1.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21277 is resolved across your whole dependency graph.

How do I detect CVE-2021-21277 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for angular-expressions, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-21277 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2021-21277 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-21277 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-21277?

CVE-2021-21277 has an EPSS (Exploit Prediction Scoring System) score of 2.7%, placing it in the 86th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-21277?

CVE-2021-21277 is classified as CWE-74 (CWE-74), Code Injection (CWE-94). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-21277 published, and has it been updated?

CVE-2021-21277 was published on February 1, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

CVE-2021-21277 — angular-expressions

HIGHFix: peerigon/angular-expressions@07edb62

CVE-2021-21277 is a high-severity (CVSS 8.8) CWE-74 vulnerability in angular-expressions. A fix is available for angular-expressions — see the affected versions and patch details below.

Angular Expressions - Remote Code Execution

Also known asGHSA-j6px-jwvv-vpwq

Published

Feb 1, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs86th percentile — riskier than 86% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

81other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

angular-expressionsnpm

69Kdownloads / week

Description

Impact

The vulnerability, reported by GoSecure Inc, allows Remote Code Execution, if you call expressions.compile(userControlledInput) where userControlledInput is text that comes from user input.

This time, the security of the package could be bypassed by using a more complex payload, using a .constructor.constructor technique.

If running angular-expressions in the browser, an attacker could run any browser script when the application code calls expressions.compile(userControlledInput).
If running angular-expressions on the server, an attacker could run any Javascript expression, thus gaining Remote Code Execution.

Patches

Users should upgrade to version 1.1.2 of angular-expressions

Workarounds

A temporary workaround might be either to :

disable user-controlled input that will be fed into angular-expressions in your application

allow only following characters in the userControlledInput :

if (/^[|a-zA-Z.0-9 :"'+-?]+$/.test(userControlledInput)) {
      var result = expressions.compile(userControlledInput);
}
else {
     result = undefined;
}

References

Removal of angular-expression sandbox

For more information

If you have any questions or comments about this advisory:

Open an issue in angular-expressions
Email us

Credits

The issue was reported by Maxime Nadeau from GoSecure, Inc.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`angular-expressions`	all versions	1.1.2`npm install angular-expressions@1.1.2`

Affected Products

1 product · 1 configurations

Application

angular-expressionspeerigon

< 1.1.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for angular-expressions, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update angular-expressions to 1.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21277 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

### Impact The vulnerability, reported by GoSecure Inc, allows Remote Code Execution, if you call `expressions.compile(userControlledInput)` where `userControlledInput` is text that comes from user input. This time, the security of the package could be bypassed by using a more complex payload, using a `.constructor.constructor` technique. * If running angular-expressions in the browser, an attacker could run any browser script when the application code calls expressions.compile(userControlledInput). * If running angular-expressions on the server, an attacker could run any Javascript express