Use After Free in Curl

CVE-2026-3805

When doing a second SMB request to the same host again, curl would wrongly use a data pointer pointing into already freed memory.

Vulnerability class: Use-After-Free

EPSS: 0.007 (51.0th percentile) — read the EPSS interpretation.

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.

Affected products

Curl — versions 8.18.0, 8.17.0, 8.16.0
Haxx Curl

Weakness classification (CWE)

CWE-416 — Use After Free

Public proof-of-concept exploits

Rat5ak/CVE-2026-3805-curl-SMB-UAF

References

2499f714-1537-4658-8207-48ae4bb9eae9 (Vendor Advisory)
2499f714-1537-4658-8207-48ae4bb9eae9 (Patch, Vendor Advisory)
2499f714-1537-4658-8207-48ae4bb9eae9 (Exploit, Third Party Advisory, Issue Tracking)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2026-3805?: CVE-2026-3805 is a high-severity vulnerability in Curl, classified under Use After Free. CVSS score: 7.5/10. Published 2026-03-11.
How severe is CVE-2026-3805?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2026-3805 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.