CVE-2026-3784 | wrong proxy connection reuse with credentials

Exp

curl would wrongly reuse an existing HTTP proxy connection doing CONNECT to a server, even if the new request uses different credentials for the HTTP proxy. The proper behavior is to create or use a separate connection.

Published: 2026-03-11 Last update: 2026-06-02 Assigner: 2499f714-1537-4658-8207-48ae4bb9eae9 Source: 2499f714-1537-4658-8207-48ae4bb9eae9
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-3784 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.29%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-3784

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-3784

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.29% +0.27%
2 2026-03-11 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-3784

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.5 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-3784

GitHub Security Advisory for CVE-2026-3784

GHSA-5q3w-6p3j-mw6p · Severity: medium — curl would wrongly reuse an existing HTTP proxy connection doing CONNECT to a server, even if the...

OS Trackers for CVE-2026-3784

vendor priority summary link
alpine — CVE-2026-3784: 1 source package rows (curl); 280 state rows across 6 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 1, open 279. https://security.alpinelinux.org/vuln/CVE-2026-3784
debian not yet assigned CVE-2026-3784 not yet assigned priority: Debian including 1 source packages (curl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-3784
redhat medium — https://access.redhat.com/security/cve/CVE-2026-3784
suse medium CVE-2026-3784 severity moderate: SUSE including 304 source package names (1.1.1-1.44:libcurl4-8.14.1-150700.7.14.1, 13.2-9.77:curl-8.14.1-slfo.1.1_6.1, …), 493 product×package rows across 98 product lines (Container private-registry/harbor-trivy-adapter, Container suse/ltss/sle12.5/sles12sp5, … (98 product lines)): Fixed 254, Known Affected 231, First Fixed 8. https://www.suse.com/security/cve/CVE-2026-3784/
ubuntu low CVE-2026-3784 low priority: Ubuntu including 1 source packages (curl), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): released 6, not-affected 2. https://ubuntu.com/security/CVE-2026-3784

Affected software / configurations for CVE-2026-3784

Vendor Product Version Raw CPE
haxx curl >= 7.7, < 8.18.0 cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*

References for CVE-2026-3784

cvelogic Threat Intelligence