CVE-2026-8458
MEDIUMDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Moderate risk: more likely to be exploited than 44% of all known CVEs.
References
Related Vulnerabilities
Other CWE-488 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-38367 | High | 8.2 | 11% | - | Fix |
| CVE-2024-6162 | High | 7.5 | 1.7% | - | Fix |
| CVE-2026-19931 | Medium | 6.5 | 1.2% | - | Fix |
| CVE-2026-80231 | Low | 3.7 | 0.9% | - | Fix |
| CVE-2025-1247 | High | 8.3 | 0.8% | - | - |
| CVE-2024-27935 | High | 7.2 | 0.7% | - | Fix |
Common questions
How do I fix CVE-2026-8458?
Upgrade curl on debian unstable to 8.21.0~rc2-1 or later.
Is CVE-2026-8458 being actively exploited?
Not that we know of. CVE-2026-8458 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.54% is the estimated probability that it will be exploited in the next 30 days. That is higher than 44% of all scored CVEs.
How severe is CVE-2026-8458?
CVE-2026-8458 has a CVSS v3 base score of 6.5, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-8458 affect?
Published advisories record a fix for curl (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-15.