CVE-2026-6253

mediumpriority · track · 0EPSS 0.007 · 54 %ileDEEUFRRUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.72% (54th) EPSS

CVSS 5.9 · medium

Is it mine?

192 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

curl might erroneously pass on credentials for a first proxy to a second proxy. This can happen when the following conditions are true: 1. curl is setup to use specific different proxies for different URL schemes 2. the first proxy needs credentials 3. the second proxy uses no credentials 4. while using the first proxy (using say `http://`), curl is asked to follow a redirect to a URL using another scheme (say `https://`), accessed using a second, different, proxy

cvss

Technical severity, 0–10. One row per scoring source.

5.9

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.15.9mediumAV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · ENISA EU

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondaryexploitability 2.2 · impact 3.6

v3.15.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-522USprimaryCWE-522US

affected products (192)

Products and version ranges known to be affected.

Fedora Linuxall versionscert_bundDEcpe:/o:fedoraproject:fedora:-
Google Container-Optimized OSall versionscert_bundDEcpe:/o:google:container-optimized_os:-
IBM AIXall versionscert_bundDEcpe:/o:ibm:aix:-
IBM AIX 7.3all versionscert_bundDEcpe:/o:ibm:aix:7.3
Oracle Linuxall versionscert_bundDEcpe:/o:oracle:linux:-
RESF Rocky Linuxall versionscert_bundDEcpe:/o:resf:rocky_linux:-
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
Red Hat JBoss Core Servicesall versionscert_bundDEcpe:/a:redhat:jboss_core_services:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
SUSE openSUSEall versionscert_bundDEcpe:/o:suse:opensuse:-
Ubuntu Linuxall versionscert_bundDEcpe:/o:canonical:ubuntu_linux:-
Dell Secure Connect Gateway< 5.36.00.16cert_bundDE
Open Source cURL< 8.20.0cert_bundDE
curl curl≤ 7.15.4 ≤7.15.4enisa_euvdEU
curl curl≤ 7.77.0 ≤7.77.0enisa_euvdEU
curl curl≤ 7.27.0 ≤7.27.0enisa_euvdEU
curl curl≤ 7.16.1 ≤7.16.1enisa_euvdEU
curl curl≤ 8.10.0 ≤8.10.0enisa_euvdEU
curl curl≤ 7.83.1 ≤7.83.1enisa_euvdEU
curl curl≤ 7.74.0 ≤7.74.0enisa_euvdEU

showing 20 of 192

advisories (5)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-1307cURL: Mehrere SchwachstellenDeutsch2026-04-28csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in cURL ausnutzen, um Sicherheitsvorkehrungen zu umgehen, vertrauliche Informationen offenzulegen oder Daten zu manipulieren.
CERTFR-2026-AVI-1351Multiples vulnérabilités dans Oracle MySQLFrançais2026-10-21vendor · certfrFR
CERTFR-2026-AVI-1385Multiples vulnérabilités dans les produits VMwareFrançais2026-10-26vendor · certfrFR
CERTFR-2026-AVI-1390Multiples vulnérabilités dans Tenable Network MonitorFrançais2026-10-27vendor · certfrFR
CURL-CVE-2026-6253proxy credentials leak over redirect-to proxy2026-04-29vendor · osvUS
curl might erroneously pass on credentials for a first proxy to a second proxy. This can happen when the following conditions are true: 1. curl is setup to use specific different proxies for different URL schemes 2. the first proxy needs credentials 3. the second proxy uses no credentials 4. while using the first proxy (using say `http://`), curl is asked to follow a redirect to a URL using another scheme (say `https://`), accessed using a second, different, proxy

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund certfr osv NVD CVE.org MITRE

published 2026-05-13modified 2026-06-17

related (1,722)

Related entries.

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Rockwell Automation Studio 5000 Logix Designer Versions 21 and later, and RSLogix 5000 Versions 16 through 20 use a key to verify Logix controllers are communicating with Rockwell…
CVE-2020-29583US	critical9.8OT critical	90.2% (100th)	KEV	2020-12-22
Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The password for this account can be found in cleartext in the fi…
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+1717 more

references (9)

External citations — patches, advisories, analysis.

https://github.com/curl/curl/releasesPatchcnnvd
https://nvd.nist.gov/vuln/detail/CVE-2026-6253 cnnvd
https://curl.se/docs/CVE-2026-6253.html enisa_euvd
https://curl.se/docs/CVE-2026-6253.json enisa_euvd
https://hackerone.com/reports/3669637 enisa_euvd
http://www.openwall.com/lists/oss-security/2026/04/29/11Mailing ListPatchThird Party Advisorynvd
https://curl.se/docs/CVE-2026-6253.htmlPatchVendor Advisorynvd
https://curl.se/docs/CVE-2026-6253.jsonVendor Advisorynvd

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