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CVE-2026-4873

28
FAUCET Score

A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.

First published: May 13, 2026Last modified: May 13, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 7.20.0, < 8.20.0CPE matchmatch criteria
cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
>= 7.20.0, <= 7.20.0CPE match
cpe:2.3:a:curl:curl:*:*:*:*:*:*:*:*
>= 7.20.1, <= 7.20.1CPE match
cpe:2.3:a:curl:curl:*:*:*:*:*:*:*:*
>= 7.21.0, <= 7.21.0CPE match
cpe:2.3:a:curl:curl:*:*:*:*:*:*:*:*
>= 7.21.1, <= 7.21.1CPE match
cpe:2.3:a:curl:curl:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.33%
Probability of exploitation in next 30 days
EPSS Percentile
25.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0033 is in the 3rd percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (10)

microsoftpatch availablevia msrc
Product: 21382-17084Fixed in: 8.11.1-7
microsoftpatch availablevia msrc
Product: azl3 curl 8.11.1-6 on Azure Linux 3.0Fixed in: 8.11.1-7
microsoftpatch availablevia msrc
Product: azl3 curl 8.11.1-7 on Azure Linux 3.0Fixed in: 8.11.1-7
microsoftpatch availablevia msrc
Product: azl3 cmake 3.30.3-13 on Azure Linux 3.0Fixed in: 3.30.3-14
microsoftpatch availablevia msrc
Product: 21207-17084Fixed in: 8.11.1-7
microsoftpatch availablevia msrc
Product: 21119-17084Fixed in: 3.30.3-14
ubuntupatch availablevia ubuntu_usn
Product: curl (noble)Fixed in: 8.5.0-2ubuntu10.9
ubuntupatch availablevia ubuntu_usn
Product: curl (questing)Fixed in: 8.14.1-2ubuntu1.3
ubuntupatch availablevia ubuntu_usn
Product: curl (resolute)Fixed in: 8.18.0-1ubuntu2.1
ubuntupatch availablevia ubuntu_usn
Product: curl (jammy)Fixed in: 7.81.0-1ubuntu1.24

Vendor Advisories (2)

microsoft2026-May/CVE-2026-4873Moderate

connection reuse ignores TLS requirement

May 12, 2026
ubuntuUSN-8227-1

curl vulnerabilities

May 4, 2026

References

curl.se / docs/CVE-2026-4873.html
PatchVendor Advisory
curl.se / docs/CVE-2026-4873.json
Vendor Advisory
hackerone.com / reports/3621851
ExploitIssue TrackingThird Party Advisory
openwall.com / lists/oss-security/2026/04/29/7
Mailing ListPatchThird Party Advisory