PatchTheCVECVE-2021-43309: An exponential ReDoS (Regular Expression Denial of Service) can be triggered in the uri-template-lite npm pack
CVE-2021-43309 is a medium-severity flaw (CVSS 5.9) affecting uri-template-lite. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
An exponential ReDoS (Regular Expression Denial of Service) can be triggered in the uri-template-lite npm package, when an attacker is able to supply arbitrary input to the "URI.expand" method
Why this priority
- Public exploit reference
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.9 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 1.0% (top 37%) |
| CISA exploited list | No |
| Weakness | CWE-1333 |
| Published | 2022-08-24 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-43309?
uri-template-lite: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2021-43309 being exploited?
CVE-2021-43309 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-43309 affect?
CVE-2021-43309 affects uri-template-lite. Severity is medium (CVSS 5.9). An exponential ReDoS (Regular Expression Denial of Service) can be triggered in the uri-template-lite npm package, when an attacker is able to supply arbitrary input to the "URI.expand" method
How urgent is CVE-2021-43309?
Priority 46/100. Public exploit reference; Remotely exploitable, no login, no user action