CVE-2021-26505
MrSwitch hello.js vulnerable to prototype pollution
Prototype pollution vulnerability in MrSwitch hello.js version 1.18.6, allows remote attackers to execute arbitrary code via hello.utils.extend function.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
Prototype pollution vulnerability in MrSwitch hello.js version 1.18.6, allows remote attackers to execute arbitrary code via hello.utils.extend function.
- Record
CVE-2021-26505- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-1321
- Updated
- 2026-11-02
CVE List No score
Prototype pollution vulnerability in MrSwitch hello.js version 1.18.6, allows remote attackers to execute arbitrary code via hello.utils.extend function.
- Record
CVE-2021-26505- Updated
- 2026-11-02
EUVDEUVD-2023-2286 No score
Prototype pollution vulnerability in MrSwitch hello.js version 1.18.6, allows remote attackers to execute arbitrary code via hello.utils.extend function.
- Record
EUVD-2023-2286- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-g3vf-47fv-8f3c
MrSwitch hello.js vulnerable to prototype pollution
A prototype pollution vulnerability in MrSwitch hello.js prior to version 1.18.8 allows remote attackers to execute arbitrary code via hello.utils.extend function.
- Record
GHSA-g3vf-47fv-8f3c- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-1321
- Updated
- 2026-11-02
OSV
Prototype pollution vulnerability in MrSwitch hello.js version 1.18.6, allows remote attackers to execute arbitrary code via hello.utils.extend function.
- Record
CVE-2021-26505- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-g3vf-47fv-8f3c
MrSwitch hello.js vulnerable to prototype pollution
A prototype pollution vulnerability in MrSwitch hello.js prior to version 1.18.8 allows remote attackers to execute arbitrary code via hello.utils.extend function.
- Record
GHSA-g3vf-47fv-8f3c- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-1321
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
hellojsnpm |
before 1.18.8 | 1.18.8 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-26505 is a critical vulnerability (CVSS 9.8) in Hello.js Project Hello.js, published August 11, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.14%, the 66th percentile. Fixed in hellojs 1.18.8.