VulnerabilityAnalyzed
CVE-2026-19931
A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, when the initial request is done using empty credentials.
CRITICAL 9.8EPSS 1.16%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.16%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, when the initial request is done using empty credentials. This can make user B's request get sent over user A's previously authenticated connection.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.16% probability · 65th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-488
- Affected
- haxx/curl
- Source
- 2499f714-1537-4658-8207-48ae4bb9eae9
References
- https://curl.se/docs/CVE-2026-19931.htmlPatch, Vendor Advisory
- https://curl.se/docs/CVE-2026-19931.jsonVendor Advisory
- https://hackerone.com/reports/3923520Exploit, Mitigation, Third Party Advisory
- https://hackerone.com/reports/3923520Exploit, Mitigation, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.