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Public proof of conceptFix available

CVE-2026-8927

A public proof of concept exists; no exploitation attested.

  • Published2026-07-03
  • Fixed in8.21.0
  • WeaknessCWE-294

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

Timeline

dates in UTC
  1. 2026-07-0307:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-8927?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-8927?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Haxx curl
BranchAffectedFixed in
8.21≥ 7.12.0, < 8.21.08.21.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • libcurlAlmaLinux:10all versions · fixed in 8.12.1-4.el10_2.4and 3 other packages
  • libcurlAlmaLinux:9all versions · fixed in 7.76.1-40.el9_8.7and 4 other packages

Vendor advisories

  • CVE-2026-8927 Red Hat Product Security258 products fixed · 21 known affected

    curl: Information disclosure due to uncleared proxy authentication state

    build-of-trustee/trustee-rhel9 as a component of Confidential Compute Attestation · openshift-sandboxed-containers/osc-podvm-payload-rhel9 as a component of Confidential Compute Attestation · snphost.src as a component of Red Hat Enterprise Linux 10 · +18 more

  • RHSA-2026:73516 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: Red Hat OpenShift Dev Spaces 3.30.2 Release.

  • RHSA-2026:72506 Red Hat Product Security49 products fixed

    Red Hat Security Advisory: curl security update

  • RHSA-2026:72476 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1

  • RHSA-2026:72475 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1

  • RHSA-2026:72470 Red Hat Product Security8 products fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1

10 more advisories

Full record on NVD

Fix

  1. Update Haxx curl to 8.21.0
  2. Vendor fix Red Hat Product Security RHSA-2026:73516 · 4 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  3. Vendor fix Red Hat Product Security RHSA-2026:72506 · 49 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  4. Vendor fix Red Hat Product Security RHSA-2026:72476 · 4 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. The steps to apply the upgraded images are different depending on the installation plan approval policy you used when installing the cert-manager Operator for Red Hat OpenShift. - If t…
  5. Vendor fix Red Hat Product Security RHSA-2026:71603 · 5 productsThe container images provided by this release, apart from the installer, should be deployed using rhui-installer utility. See the official documentation for more details.
  6. Vendor fix CISA ICSA-26-293-05 · 2 productsUpdate to CMU Firmware version 13.9.1
  7. Vendor fix CISA ICSA-26-293-05 · 1 productUpdate to CMU Firmware version 13.9.1 or 13.7.9 (when available)

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionpoc2026-07-06
  • OpenCVESSVC decisionpoc—
  • CISA-ADPCVSS 3.19.12026-07-06
  • CNAweakness (CWE)CWE-294read 2026-10-23
  • NVDweakness (CWE)CWE-294read 2026-10-23
  • FIRST EPSSEPSS score0.5 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
2026-07-03
Last Modified
2026-09-15
NVD status
Modified

Frequently asked questions

What is CVE-2026-8927?

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

Is CVE-2026-8927 actively exploited?

A proof-of-concept exploit exists for CVE-2026-8927, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-8927?

CVE-2026-8927 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

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