Vulnerability in Curl
CVE-2026-4873
A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.004 (27.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.000
Affected products
Weakness classification (CWE)
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 (Patch, Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-4873?
- CVE-2026-4873 is a medium-severity vulnerability in Curl, classified under Cleartext Transmission of Sensitive Information. CVSS score: 5.9/10. Published 2026-05-13.
- How severe is CVE-2026-4873?
- Medium severity. CVSS v3 base score is 5.9 out of 10.