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🛡️ CVE-2026-6276 — curl

🟠 CVSS 7.5 — High ⚠️ Exploit Public CWE-319 NVD
7.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Using libcurl, when a custom Host: header is first set for an HTTP request

and a second request is subsequently done using the same *easy handle* but

without the custom Host: header set, the second request would use stale

information and pass on cookies meant for the first host in the second

request. Leak them.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-6276 is classified as CWE-319: Cleartext Transmission of Sensitive Information. Sensitive data crosses the network without encryption and can be read or altered in transit.

Affected software

CVE-2026-6276 is recorded against 1 package.

  • curl (from 7.71.0 up to 8.20.0)

Timeline and source

Published on 13 May 2026 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

curl.se
curl.se
hackerone.com
www.openwall.com
hackerone.com

Other advisories for this package

curl has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-319: Cleartext Transmission of Sensitive Information) in other software:

CVE-2026-6276 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 7.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-319
Public Exploit ⚠️ Yes
Source NVD
Published 2026-05-13
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
curl 7.71.0 8.20.0

References

Exploit, Issue Tracking, Third Party Advisory https://hackerone.com/reports/3671818
Exploit, Issue Tracking, Third Party Advisory https://hackerone.com/reports/3671818

Exploit Protection

Are you running curl?

CVE-2026-6276 carries CVSS 7.5 High rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

Check My Site For CVE-2026-6276 →

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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