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Vulnerability record · CVE-2026-80229 · published 6 September 2026

CVE-2026-80229: Haxx curl use after free vulnerability

Haxx · Curl

When performing transfers via libcurl’s multi interface, pooled TLS connections can outlive their originating easy handles. In OpenSSL 3 provider configurations, libcurl attaches an allocated library context to the easy handle's state and passes it to OpenSSL without acquiring an ownership reference; destroying the easy handle prematurely frees this context while the active connection retains a dangling pointer, leading to a heap-use-after-free upon subsequent I/O or post-handshake operations.

7.5 CVSS 3.1 High EPSS 0.56% · top 55.4% CWE-416 · Use after free
7.5CVSS 3.1 base score
0.56%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 1 tagged exploit
15 Sep 2026Last modified by NVD

Description

When performing transfers via libcurl’s multi interface, pooled TLS connections can outlive their originating easy handles. In OpenSSL 3 provider configurations, libcurl attaches an allocated library context to the easy handle's state and passes it to OpenSSL without acquiring an ownership reference; destroying the easy handle prematurely frees this context while the active connection retains a dangling pointer, leading to a heap-use-after-free upon subsequent I/O or post-handshake operations.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://curl.se/docs/CVE-2026-80229.html PatchVendor Advisory
https://curl.se/docs/CVE-2026-80229.json Vendor Advisory
https://hackerone.com/reports/3969255 ExploitMitigationThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-80229), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.