A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

1. May 13, 2026 · NIST NVD

   Detected

   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.

2. Sep 15, 2026 · NIST NVD

   Updated

   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.

Affected

• cpe haxx/curlversion unspecified

Sources

• CVE.orgVulnerability recordCVE-2026-4873

  Official CVE identifier

  cve.org
• NIST NVDVulnerability recordCVE-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

  nvd.nist.gov

References

• Mailing List · openwall.com
• Patch · curl.se
• Vendor Advisory · curl.se
• Exploit · hackerone.com