Description
curl's WebSocket code did not update the 32-bit mask pattern for each new outgoing frame as the specification says. Instead it used a fixed mask that persisted and was used throughout the entire connection. A predictable mask pattern allows for a malicious server to induce traffic between the two communicating parties that could be interpreted by an involved proxy (configured or transparent) as genuine, real, HTTP traffic with content and thereby poison its cache. That cached poisoned content could then be served to all users of that proxy.
Affected products
haxx: curl
References6
- curl.se/docs/CVE-2025-10148.html PatchVendor Advisory
- curl.se/docs/CVE-2025-10148.json Vendor Advisory
- www.openwall.com/lists/oss-security/2025/09/10/2 Mailing ListPatchThird Party Advisory
- hackerone.com/reports/3330839 Issue TrackingThird Party Advisory
- www.openwall.com/lists/oss-security/2025/09/10/3 Mailing ListThird Party Advisory
- www.openwall.com/lists/oss-security/2025/09/10/4 Mailing ListThird Party Advisory
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - EPSS — exploit probability
- 1% percentile: 45 · as of 8 November 2026
- CWE
- CWE-340
Could this be exploited in your environment?
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