🔐 CVE Alert

CVE-2026-4873

UNKNOWN 0.0

connection reuse ignores TLS requirement

CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th

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.

Vendor curl
Product curl
Published May 13, 2026
Last Updated May 13, 2026
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Affected Versions

curl / curl
8.19.0 ≤ 8.19.0 8.18.0 ≤ 8.18.0 8.17.0 ≤ 8.17.0 8.16.0 ≤ 8.16.0 8.15.0 ≤ 8.15.0 8.14.1 ≤ 8.14.1 8.14.0 ≤ 8.14.0 8.13.0 ≤ 8.13.0 8.12.1 ≤ 8.12.1 8.12.0 ≤ 8.12.0 8.11.1 ≤ 8.11.1 8.11.0 ≤ 8.11.0 8.10.1 ≤ 8.10.1 8.10.0 ≤ 8.10.0 8.9.1 ≤ 8.9.1 8.9.0 ≤ 8.9.0 8.8.0 ≤ 8.8.0 8.7.1 ≤ 8.7.1 8.7.0 ≤ 8.7.0 8.6.0 ≤ 8.6.0 8.5.0 ≤ 8.5.0 8.4.0 ≤ 8.4.0 8.3.0 ≤ 8.3.0 8.2.1 ≤ 8.2.1 8.2.0 ≤ 8.2.0 8.1.2 ≤ 8.1.2 8.1.1 ≤ 8.1.1 8.1.0 ≤ 8.1.0 8.0.1 ≤ 8.0.1 8.0.0 ≤ 8.0.0 7.88.1 ≤ 7.88.1 7.88.0 ≤ 7.88.0 7.87.0 ≤ 7.87.0 7.86.0 ≤ 7.86.0 7.85.0 ≤ 7.85.0 7.84.0 ≤ 7.84.0 7.83.1 ≤ 7.83.1 7.83.0 ≤ 7.83.0 7.82.0 ≤ 7.82.0 7.81.0 ≤ 7.81.0 7.80.0 ≤ 7.80.0 7.79.1 ≤ 7.79.1 7.79.0 ≤ 7.79.0 7.78.0 ≤ 7.78.0 7.77.0 ≤ 7.77.0 7.76.1 ≤ 7.76.1 7.76.0 ≤ 7.76.0 7.75.0 ≤ 7.75.0 7.74.0 ≤ 7.74.0 7.73.0 ≤ 7.73.0 7.72.0 ≤ 7.72.0 7.71.1 ≤ 7.71.1 7.71.0 ≤ 7.71.0 7.70.0 ≤ 7.70.0 7.69.1 ≤ 7.69.1 7.69.0 ≤ 7.69.0 7.68.0 ≤ 7.68.0 7.67.0 ≤ 7.67.0 7.66.0 ≤ 7.66.0 7.65.3 ≤ 7.65.3 7.65.2 ≤ 7.65.2 7.65.1 ≤ 7.65.1 7.65.0 ≤ 7.65.0 7.64.1 ≤ 7.64.1 7.64.0 ≤ 7.64.0 7.63.0 ≤ 7.63.0 7.62.0 ≤ 7.62.0 7.61.1 ≤ 7.61.1 7.61.0 ≤ 7.61.0 7.60.0 ≤ 7.60.0 7.59.0 ≤ 7.59.0 7.58.0 ≤ 7.58.0 7.57.0 ≤ 7.57.0 7.56.1 ≤ 7.56.1 7.56.0 ≤ 7.56.0 7.55.1 ≤ 7.55.1 7.55.0 ≤ 7.55.0 7.54.1 ≤ 7.54.1 7.54.0 ≤ 7.54.0 7.53.1 ≤ 7.53.1 7.53.0 ≤ 7.53.0 7.52.1 ≤ 7.52.1 7.52.0 ≤ 7.52.0 7.51.0 ≤ 7.51.0 7.50.3 ≤ 7.50.3 7.50.2 ≤ 7.50.2 7.50.1 ≤ 7.50.1 7.50.0 ≤ 7.50.0 7.49.1 ≤ 7.49.1 7.49.0 ≤ 7.49.0 7.48.0 ≤ 7.48.0 7.47.1 ≤ 7.47.1 7.47.0 ≤ 7.47.0 7.46.0 ≤ 7.46.0 7.45.0 ≤ 7.45.0 7.44.0 ≤ 7.44.0 7.43.0 ≤ 7.43.0 7.42.1 ≤ 7.42.1 7.42.0 ≤ 7.42.0 7.41.0 ≤ 7.41.0 7.40.0 ≤ 7.40.0 7.39.0 ≤ 7.39.0 7.38.0 ≤ 7.38.0 7.37.1 ≤ 7.37.1 7.37.0 ≤ 7.37.0 7.36.0 ≤ 7.36.0 7.35.0 ≤ 7.35.0 7.34.0 ≤ 7.34.0 7.33.0 ≤ 7.33.0 7.32.0 ≤ 7.32.0 7.31.0 ≤ 7.31.0 7.30.0 ≤ 7.30.0 7.29.0 ≤ 7.29.0 7.28.1 ≤ 7.28.1 7.28.0 ≤ 7.28.0 7.27.0 ≤ 7.27.0 7.26.0 ≤ 7.26.0 7.25.0 ≤ 7.25.0 7.24.0 ≤ 7.24.0 7.23.1 ≤ 7.23.1 7.23.0 ≤ 7.23.0 7.22.0 ≤ 7.22.0 7.21.7 ≤ 7.21.7 7.21.6 ≤ 7.21.6 7.21.5 ≤ 7.21.5 7.21.4 ≤ 7.21.4 7.21.3 ≤ 7.21.3 7.21.2 ≤ 7.21.2 7.21.1 ≤ 7.21.1 7.21.0 ≤ 7.21.0 7.20.1 ≤ 7.20.1 7.20.0 ≤ 7.20.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗
curl.se: https://curl.se/docs/CVE-2026-4873.json curl.se: https://curl.se/docs/CVE-2026-4873.html hackerone.com: https://hackerone.com/reports/3621851 openwall.com: http://www.openwall.com/lists/oss-security/2026/04/29/7

Credits

Arkadi Vainbrand Daniel Stenberg