What’s Vulnerable › Vulnerabilities

CVE-2026-8458: wrong reuse for different services

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-03 · updated 2026-09-15
• Weakness: CWE-488

Description

libcurl might in some circumstances reuse the wrong connection when asked to do Negotiate-authenticated ones, even when they are set to use different "services". libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different services.

Affected products

• curl: from 7.46.0 before 8.20.0 — fixed in 8.20.0

How to fix

Upgrade to a fixed version: curl 8.20.0. Check the vendor advisory for mitigations.

References

• https://curl.se/docs/CVE-2026-8458.html
• https://curl.se/docs/CVE-2026-8458.json
• https://hackerone.com/reports/3721183
• https://hackerone.com/reports/3721183

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