What is CVE-2021-3749?

CVE-2021-3749 is a high-severity vulnerability in Axios, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2021-08-31.

How severe is CVE-2021-3749?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-3749 known to be exploited?

47 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Resource exhaustion in Axios

CVE-2021-3749

axios is vulnerable to Inefficient Regular Expression Complexity

Vulnerability class: ReDoS (Regular Expression Denial of Service)

Published 2021-08-31 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.085 (95.0th percentile), scored 2026-11-01.

Low probability of exploitation in the next 30 days, but still tracked. 95th percentile — 95.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.085 · newest: 0.085 · change: 0.000

Affected products

Axios
Axios Axios/axios — versions unspecified
Oracle Goldengate
Siemens Sinec Ins — versions 1.0

Weakness classification (CWE)

Public proof-of-concept exploits

References

huntr.dev/bounties/1e8f07fc-c384-4ff9-8498-0690de2e8c31 (Exploit, Patch, Third Party Advisory)
github.com/axios/axios/commit/5b457116e31db0e88fede6c428e969e87f290929 (Patch, Third Party Advisory)
lists.apache.org/thread.html/r7324ecc35b8027a51cb6ed629490fcd3b2d7cf01c424746ed… (mailing-list)
lists.apache.org/thread.html/rfc5c478053ff808671aef170f3d9fc9d05cc1fab8fb64431e… (mailing-list)
lists.apache.org/thread.html/r216f0fd0a3833856d6a6a1fada488cadba45f447d87010024… (mailing-list)
lists.apache.org/thread.html/r3ae6d2654f92c5851bdb73b35e96b0e4e3da39f28ac7a1b15… (mailing-list)
lists.apache.org/thread.html/ra15d63c54dc6474b29f72ae4324bcb03038758545b3ab8008… (mailing-list)
lists.apache.org/thread.html/r74d0b359408fff31f87445261f0ee13bdfcac7d66f6b8e846… (mailing-list)
lists.apache.org/thread.html/rc263bfc5b53afcb7e849605478d73f5556eb0c00d1f912084… (mailing-list)
lists.apache.org/thread.html/r4bf1b32983f50be00f9752214c1b53738b621be1c2b0dbd68… (mailing-list)

Frequently asked questions

What is CVE-2021-3749?: CVE-2021-3749 is a high-severity vulnerability in Axios, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2021-08-31.
How severe is CVE-2021-3749?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-3749 known to be exploited?: 47 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.