cURL up to 8.18.0 OAuth2 Bearer Token insufficiently protected credentials

CVSS Meta Temp Score
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CTI Interest Score
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4.4$0-$5k0.00

Summaryinfo

A vulnerability marked as problematic has been reported in cURL. This vulnerability affects unknown code of the component OAuth2 Bearer Token Handler. The manipulation leads to insufficiently protected credentials. This vulnerability is referenced as CVE-2026-3783. Remote exploitation of the attack is possible. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in cURL and classified as problematic. This issue affects an unknown code of the component OAuth2 Bearer Token Handler. The manipulation with an unknown input leads to a insufficiently protected credentials vulnerability. Using CWE to declare the problem leads to CWE-522. The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval. Impacted is confidentiality. The summary by CVE is:

When an OAuth2 bearer token is used for an HTTP(S) transfer, and that transfer performs a redirect to a second URL, curl could leak that token to the second hostname under some circumstances. If the hostname that the first request is redirected to has information in the used .netrc file, with either of the `machine` or `default` keywords, curl would pass on the bearer token set for the first host also to the second one.

The weakness was published by Spectreglobalsec. It is possible to read the advisory at curl.se. The identification of this vulnerability is CVE-2026-3783 since 03/08/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1552 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 302096 (SUSE SLES15 / openSUSE 15 Security Update : curl (SUSE-SU-2026:0885-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (302096) and CERT Bund (WID-SEC-2026-0690). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Open Source cURL

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.5
VulDB Meta Temp Score: 4.4

VulDB Base Score: 3.7
VulDB Temp Score: 3.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 5.3
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Insufficiently protected credentials
CWE: CWE-522
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 302096
Nessus Name: SUSE SLES15 / openSUSE 15 Security Update : curl (SUSE-SU-2026:0885-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

03/08/2026 CVE reserved
03/11/2026 +3 days Advisory disclosed
03/11/2026 +0 days VulDB entry created
03/14/2026 +3 days VulDB entry last update

Sourcesinfo

Advisory: curl.se
Researcher: Spectreglobalsec
Status: Confirmed

CVE: CVE-2026-3783 (🔒)
GCVE (CVE): GCVE-0-2026-3783
GCVE (VulDB): GCVE-100-350375
CERT Bund: WID-SEC-2026-0690 - cURL: Mehrere Schwachstellen

Entryinfo

Created: 03/11/2026 12:49
Updated: 03/14/2026 06:29
Changes: 03/11/2026 12:49 (54), 03/12/2026 01:19 (7), 03/13/2026 19:06 (2), 03/14/2026 06:29 (12)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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