# CVE-2026-107928: curl information leak uploading over WebSockets with GnuTLS

Source: https://junglewise.ai/threats/cve-2026-107928-when-curl-is-built-with-gnutls-a-malicious-websocket-server-can  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-107928 · Severity: info · Published 2026-10-20

curl is a widely-used tool for transferring data over networks. When built with the GnuTLS security library and connecting to a malicious WebSocket server, an attacker can trick curl into reading and transmitting memory from beyond its intended boundaries. This could leak sensitive data to the attacker, though crashes are also likely outcomes.

Technologies: [Curl](https://junglewise.ai/threats/technologies/curl-curl). Vendors: [Curl](https://junglewise.ai/threats/vendors/curl).

## Quick answers

**Is CVE-2026-107928 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-107928 being exploited in the wild.

**How severe is CVE-2026-107928?** Informational severity, published 20 October 2026.

**Which products and versions are affected?** Curl 7.86.0 to 8.22.0; also 8.15.0-8.16.1, 8.17.0-8.20.1, 8.21.0-8.22.0.

**Is there a fix for CVE-2026-107928?** Yes: fixed in 8.23.0; 8.20.2 (8.20.x branch); 8.16.2 (8.16.x branch); 8.14.3 (8.14.x branch). Until then: Use a different TLS backend instead of GnuTLS when performing WebSocket transfers, or disable WebSocket functionality if not required. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-107928 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-107928?** Check whether you run Curl at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 8.23.0; 8.20.2 (8.20.x branch); 8.16.2 (8.16.x branch); 8.14.3 (8.14.x branch)

Use a different TLS backend instead of GnuTLS when performing WebSocket transfers, or disable WebSocket functionality if not required.

## Technical details

A buffer over-read in curl's WebSocket handling occurs when GnuTLS's gnutls_record_send() returns more bytes sent than were provided during a blocked send, followed by an automated WebSocket PONG response. The vulnerability is reachable only when curl uses the GnuTLS TLS backend for WebSocket uploads. Exploitation requires a network-accessible malicious WebSocket server and results in heap memory disclosure or crash.

## Affected products

- curl curl 7.86.0 to 8.22.0; also 8.15.0-8.16.1, 8.17.0-8.20.1, 8.21.0-8.22.0

## Timeline

- 2026-10-14: disclosed
- 2026-10-14: patched

## References

- [https://curl.se/docs/CVE-2026-107928.html](https://curl.se/docs/CVE-2026-107928.html)
- [https://curl.se/docs/CVE-2026-107928.json](https://curl.se/docs/CVE-2026-107928.json)

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