CVE-2026-107928: info leak uploading over WebSockets with GnuTLS

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-20 · updated 2026-10-30
Weakness: CWE-126

Description

When curl is built with GnuTLS, a malicious WebSocket server can make curl send memory past its send buffer. This is due to an out of bounds read following when `gnutls_record_send()` returns a number of bytes sent **greater than the number of bytes it was given to send**. GnuTLS does that after a blocked send.

Affected products

curl: from 8.22.0 through 8.22.0; from 8.21.0 through 8.21.0; from 8.20.0 through 8.20.0; from 8.19.0 through 8.19.0; from 8.18.0 through 8.18.0; from 8.17.0 through 8.17.0

References

https://curl.se/docs/CVE-2026-107928.html
https://curl.se/docs/CVE-2026-107928.json
https://hackerone.com/reports/4099194
https://hackerone.com/reports/4099194

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