curl vulnerability

libcurl had a flaw that when instructed to clear proxy authentication credentials which made it not do so, leaving the old credentials around to get used for subsequent transfers that should not know nor use them.

Published 3 Jul 2026Updated 15 Sep 20266 sources
CVSS 9.8 ✓ VERIFIED REFERENCE

What happened

libcurl had a flaw that when instructed to clear proxy authentication credentials which made it not do so, leaving the old credentials around to get used for subsequent transfers that should not know nor use them.

Affected versions

curl: 8.8.0 through before 8.14.2 (semver); 8.15.0 through before 8.16.1 (semver); 8.17.0 through before 8.20.1 (semver); d5e83eb745762f48d8fafadc5df5dd3ae8d8941e through before 88c7e16cceec816a2df45c899d49b1e85513f193 (git); 8.20.0; 8.19.0; 8.18.0; 8.17.0; 8.16.0; 8.15.0; 8.14.1; 8.14.0; 8.13.0; 8.12.1; 8.12.0; 8.11.1; 8.11.0; 8.10.1; 8.10.0; 8.9.1; 8.9.0; 8.8.0 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

RepositoryAuthorFirst seenReference
hackerone.comNVD reference2026-07-03Verified