Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-4873

CVE-2026-4873MEDIUM

curl curl — connection reuse ignores TLS requirement

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   H   N   N  U  H  N  N    5.9   .0036   27.4     —

AFFECTED
  Product  Versions                                    Fixed
  curl     7.20.0 –                                    —
  curl     ec3bb8f727405642a471b4b1b9eb0118fc003104 –  —
  curl     8.19.0 –                                    —

TIMELINE
  Mar 26  Reserved by curl
  May 13  Published (CNA: curl)
  Sep 15  EXPLOIT PUBLISHED — CVE-2026-4873 (curl). Public exploit reference added.

CWE-295, CWE-319 · CNA: curl · CVSS v3.1 · 4 references · NVD status: Modified

Description

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
March 26, 2026	Reserved	Reserved by curl
May 13, 2026	Published	Published (CNA: curl)
September 15, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-4873 (curl). Public exploit reference added.

Affected

Affected products and packages — 3 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
curl	curl	—	7.20.0	—
curl	curl	—	ec3bb8f727405642a471b4b1b9eb0118fc003104	—
curl	curl	—	8.19.0	—

Weaknesses

CWE-295 · CWE-319

References (4)

http://www.openwall.com/lists/oss-security/2026/04/29/7 [Mailing List, Patch, Third Party Advisory]
https://curl.se/docs/CVE-2026-4873.html [Patch, Vendor Advisory]
https://curl.se/docs/CVE-2026-4873.json [Vendor Advisory]
https://hackerone.com/reports/3621851 [Exploit, Issue Tracking, Third Party Advisory]

Authoritative record: CVE-2026-4873 at cve.org

Vendors: curl

Weaknesses: CWE-295 · CWE-319

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-4873 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.