CVE-2026-86413 curl CVE debrief

Who should care

Defenders and administrators using curl versions 8.22.0 and 8.21.0 with Negotiate authentication should assess their deployment contexts for potential credential exposure. This includes verifying curl versions for vulnerability, reviewing deployment contexts, and considering compensating controls for credential protection. Security teams and vulnerability management teams should prioritize verifying affected curl versions and assessing potential impacts on

Why it matters

Defenders should care about CVE-2026-86413 because it involves potential credential exposure in curl when using Negotiate authentication with redirects, affecting specific versions.

• Potential credential exposure when using Negotiate authentication with redirects
• Need to verify curl versions for vulnerability
• Possible impact on systems using curl with Negotiate authentication

Technical summary

The curl project reported a vulnerability where Negotiate credentials could be sent to an unrelated second origin when asked to redirect there, potentially exposing credentials. This issue affects curl versions 8.22.0 and 8.21.0. The vulnerability highlights the need for defenders to verify curl versions for potential credential exposure when using Negotiate authentication with redirects and to assess their deployment contexts accordingly. The technical impact involves potential credential exposure due to improper handling of Negotiate authentication credentials during redirects.

Defensive priority

Defenders should prioritize verifying curl versions 8.22.0 and 8.21.0 for potential credential exposure when using Negotiate authentication with redirects.

Recommended defensive actions

• Verify curl versions 8.22.0 and 8.21.0 for potential credential exposure
• Assess deployment contexts using Negotiate authentication with redirects
• Consider compensating controls for credential protection
• Review vendor guidance for affected curl versions
• Conduct exposure reviews for systems using curl with Negotiate authentication
• Implement monitoring for suspicious activity related to curl usage
• Track exceptions and retest remediated assets

Evidence notes

The CVE record and source item provide limited information about the vulnerability, primarily focusing on the credential exposure issue when using Negotiate authentication with redirects in curl. Evidence is limited to CVE metadata and source-provided details. Defenders should verify curl versions 8.22.0 and 8.21.0 for potential credential exposure and assess deployment contexts using Negotiate authentication with redirects.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.