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Vulnerabilities

Vulnerability · CVE-2026-6276

Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the s

Published May 13, 2026 · catalog updated Oct 18, 2026 · Using libcurl, when a

Check if you run it

No confirmed exploitation is on record for CVE-2026-6276. EPSS is 0.35%. Act only if a listed version of Using libcurl, when a is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Using libcurl, when a).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Advisory link
Affected products
Alpine:v3.21 curl · Alpine:v3.22 curl · Alpine:v3.23 curl · Alpine:v3.24 curl · cpe haxx/curl

Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Alpine:v3.21 curl7.71.0 → 8.14.1-r3
  • Alpine:v3.22 curl7.71.0 → 8.14.1-r4
  • Alpine:v3.23 curl7.71.0 → 8.20.0-r0
  • Alpine:v3.24 curl7.71.0 → 8.20.0-r0
  • cpe haxx/curlversion unspecified

How to fix CVE-2026-6276

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-6276. EPSS is 0.35%. Act only if a listed version of Using libcurl, when a is installed.

Which versions are affected?

Compare what you have installed with 7.71.0 → 8.14.1-r3, 7.71.0 → 8.14.1-r4, 7.71.0 → 8.20.0-r0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-319: Cleartext Transmission of Sensitive Information; CWE-346. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 13, 2026 · NIST NVD

    Detected

    Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

  2. Sep 15, 2026 · NIST NVD

    Updated

    Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

  3. Oct 18, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    curl fixed in 8.14.1-r3; curl fixed in 8.14.1-r4; curl fixed in 8.20.0-r0; curl fixed in 8.20.0-r0

  4. Oct 18, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    curl fixed in 8.14.1-r3

  5. Oct 18, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    curl fixed in 8.14.1-r4

  6. Oct 18, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    curl fixed in 8.20.0-r0

  7. Oct 18, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

Sources

  • CVE.orgVulnerability recordCVE-2026-6276

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-6276

    30-day exploitation probability 0.3%

    first.org
  • NIST NVDVulnerability recordCVE-2026-6276

    Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the second request would use stale information and pass on cookies meant for the first ho

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryALPINE-CVE-2026-6276
    osv.dev
  • Trivy Vulnerability DBPackage advisoryALPINE-CVE-2026-6276

    Using libcurl, when a custom header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom header set, the second request would use stale information and pass on cookies meant for the first host in the second

    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.