VDB-224655 · CVE-2023-27536 · EUVD-2023-31291

libcurl up to 7.x Connection Reuse authentication bypass

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4.4	$0-$5k	0.00

Summaryinfo

A vulnerability marked as problematic has been reported in libcurl up to 7.x. This affects an unknown part of the component Connection Reuse Handler. Performing a manipulation results in authentication bypass. This vulnerability is known as CVE-2023-27536. 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 libcurl up to 7.x (Network Utility Software). It has been classified as problematic. This affects an unknown code of the component Connection Reuse Handler. The manipulation with an unknown input leads to a authentication bypass vulnerability. CWE is classifying the issue as CWE-305. The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error. This is going to have an impact on confidentiality. The summary by CVE is:

An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPT_GSSAPI_DELEGATION option. This vulnerability affects krb5/kerberos/negotiate/GSSAPI transfers and could potentially result in unauthorized access to sensitive information. The safest option is to not reuse connections if the CURLOPT_GSSAPI_DELEGATION option has been changed.

The weakness was published 03/31/2023. It is possible to read the advisory at hackerone.com. This vulnerability is uniquely identified as CVE-2023-27536 since 03/02/2023. The exploitability is told to be difficult. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 276313 (TencentOS Server 3: curl (TSSA-2023:0172)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 8.0.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (276313) and EUVD (EUVD-2023-31291). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Network Utility Software

Name

libcurl

Version

License

open-source

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: 3.1
VulDB Temp Score: 3.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.9
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Authentication bypass
CWE: CWE-305 / CWE-287
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 276313
Nessus Name: TencentOS Server 3: curl (TSSA-2023:0172)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: libcurl 8.0.0

Timelineinfo

03/02/2023 🔍
03/31/2023 +28 days 🔍
03/31/2023 +0 days 🔍
11/24/2025 +968 days 🔍

Sourcesinfo

Advisory: FEDORA-2023-7e7414e64d
Status: Confirmed

CVE: CVE-2023-27536 (🔍)
GCVE (CVE): GCVE-0-2023-27536
GCVE (VulDB): GCVE-100-224655
EUVD: 🔍

Entryinfo

Created: 03/31/2023 09:13
Updated: 11/24/2025 00:25
Changes: 03/31/2023 09:13 (39), 04/20/2023 20:35 (1), 06/12/2023 16:13 (16), 02/14/2025 18:04 (26), 11/17/2025 11:26 (1), 11/24/2025 00:25 (2)
Complete: 🔍
Cache ID: 216::103