CVE-2026-8927

CRITICAL 9.1

env-set cross-proxy Digest auth state leak

CVSS Score

9.1

EPSS Score

0.0%

EPSS Percentile

0th

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

CWE	CWE-294
Vendor	curl
Product	curl
Published	Jul 3, 2026
Last Updated	Sep 15, 2026

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Affected Versions

curl / curl

7.12.0 < 8.14.2 8.15.0 < 8.16.1 8.17.0 < 8.20.1

curl / curl

fc6eff13b5414caf6edf22d73a3239e074a04216 < 5c225384b8d52c67ce8259c6e4203bc57aacb567

curl / curl

8.20.0 8.19.0 8.18.0 8.17.0 8.16.0 8.15.0 8.14.1 8.14.0 8.13.0 8.12.1 8.12.0 8.11.1 8.11.0 8.10.1 8.10.0 8.9.1 8.9.0 8.8.0 8.7.1 8.7.0 8.6.0 8.5.0 8.4.0 8.3.0 8.2.1 8.2.0 8.1.2 8.1.1 8.1.0 8.0.1 8.0.0 7.88.1 7.88.0 7.87.0 7.86.0 7.85.0 7.84.0 7.83.1 7.83.0 7.82.0 7.81.0 7.80.0 7.79.1 7.79.0 7.78.0 7.77.0 7.76.1 7.76.0 7.75.0 7.74.0 7.73.0 7.72.0 7.71.1 7.71.0 7.70.0 7.69.1 7.69.0 7.68.0 7.67.0 7.66.0 7.65.3 7.65.2 7.65.1 7.65.0 7.64.1 7.64.0 7.63.0 7.62.0 7.61.1 7.61.0 7.60.0 7.59.0 7.58.0 7.57.0 7.56.1 7.56.0 7.55.1 7.55.0 7.54.1 7.54.0 7.53.1 7.53.0 7.52.1 7.52.0 7.51.0 7.50.3 7.50.2 7.50.1 7.50.0 7.49.1 7.49.0 7.48.0 7.47.1 7.47.0 7.46.0 7.45.0 7.44.0 7.43.0 7.42.1 7.42.0 7.41.0 7.40.0 7.39.0 7.38.0 7.37.1 7.37.0 7.36.0 7.35.0 7.34.0 7.33.0 7.32.0 7.31.0 7.30.0 7.29.0 7.28.1 7.28.0 7.27.0 7.26.0 7.25.0 7.24.0 7.23.1 7.23.0 7.22.0 7.21.7 7.21.6 7.21.5 7.21.4 7.21.3 7.21.2 7.21.1 7.21.0 7.20.1 7.20.0 7.19.7 7.19.6 7.19.5 7.19.4 7.19.3 7.19.2 7.19.1 7.19.0 7.18.2 7.18.1 7.18.0 7.17.1 7.17.0 7.16.4 7.16.3 7.16.2 7.16.1 7.16.0 7.15.5 7.15.4 7.15.3 7.15.2 7.15.1 7.15.0 7.14.1 7.14.0 7.13.2 7.13.1 7.13.0 7.12.3 7.12.2 7.12.1 7.12.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

curl.se: https://curl.se/docs/CVE-2026-8927.json curl.se: https://curl.se/docs/CVE-2026-8927.html hackerone.com: https://hackerone.com/reports/3744543

Credits

Ady Elouej Daniel Stenberg