VDB
CVE-2026-4873
CVE-2026-4873
PUBLISHED
CVSS 5.9 MEDIUM
connection reuse ignores TLS requirement
Reported by curl · Published May 13, 2026
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.
Fixed versions
Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.
| Package | Ecosystem | Fixed in |
|---|---|---|
| curl | haxx | 8.20.0 |
Risk scores
CVSS 3.1
5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
| Vendor | Product | Versions |
|---|---|---|
| curl | curl | 7.20.0, 8.15.0, 8.17.0 |
| curl | curl | ec3bb8f727405642a471b4b1b9eb0118fc003104 |
| curl | curl | 8.19.0, 8.18.0, 8.17.0 |
| curl | curl | 7.20.0, 7.21.1, 7.21.0 |
| alpine | curl | 0, 0, 0 |
Timeline
- Apr 29, 2026 PoC Published (2 in total, the first dated here)
- May 13, 2026 CVE Published
- May 18, 2026 EPSS Score (30 in total, the first dated here)
- Jun 2, 2026 Security Advisory (6 in total, the first dated here)
- Jul 27, 2026 Coalition ESS Score
- Aug 11, 2026 Distribution Patch (4 in total, the first dated here)
Query this with the API
The same record, from the CLI:
vulnetix vdb vuln CVE-2026-4873
vulnetix vdb fixes CVE-2026-4873Or with curl, using the org id and key from your account page:
curl -s -H "Authorization: ApiKey ${VULNETIX_ORG_ID}:${VULNETIX_API_KEY}" \
"https://api.vdb.vulnetix.com/v2/vuln/CVE-2026-4873/fixes/registry"The Community plan is free and allows 50 queries a day. Get a free API key · API quickstart