HOMEVULNERABILITIESCVE-2026-6276
HIGH

CVE-2026-6276

Published: May 13, 2026· Updated: May 14, 2026

7.5
CVSS v3.1
EPSS:0.02%probability of exploitation in 30 daysPercentile:5.2th

Official 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.

NVD Source

Technical Analysis

CVE-2026-6276 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

haxx1 product
curl
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://curl.se/docs/CVE-2026-6276.html
ADVISORYhttps://hackerone.com/reports/3671818
ADVISORYhttp://www.openwall.com/lists/oss-security/2026/04/29/13
ADVISORYhttps://hackerone.com/reports/3671818

All References (5)

→
https://curl.se/docs/CVE-2026-6276.htmlPatch · Vendor Advisory
→
https://curl.se/docs/CVE-2026-6276.jsonProduct
→
https://hackerone.com/reports/3671818Exploit · Issue Tracking · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2026/04/29/13Mailing List · Third Party Advisory
→
https://hackerone.com/reports/3671818Exploit · Issue Tracking · Third Party Advisory

Quick Facts

CVE IDCVE-2026-6276
CVSS Score7.5 / 10
SeverityHIGH
CISA KEVNo
EPSS (30d)0.02%
Affected1 vendor
PublishedMay 13, 2026

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-6276 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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