CVE-2026-9546

A flaw was found in libcurl. This vulnerability causes the HTTP Referer header to persist even after it has been explicitly cleared. This can lead to the previous referrer string being unintentionally reused and sent in subsequent requests, potentially disclosing sensitive information to unintend...

Security Bulletin: IBM WinCollect Agent is vulnerable to using components with known vulnerabilities

Summary Multiple components with known vulnerabilities were addressed in this release of IBM WinCollect Agent Vulnerability Details CVEID:CVE-2026-5545 DESCRIPTION: libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTPS request after a...

Access Control Bypass

Overview Affected versions of this package are vulnerable to Access Control Bypass due to the omission of SSH host verification options in the --proto-default process. An attacker can intercept or impersonate an SSH server by exploiting the lack of host verification during connection establishmen...

Use After Free

Overview Affected versions of this package are vulnerable to Use After Free in the curleasycleanup process after configuring an HTTP/2 stream-dependency tree using CURLOPTSTREAMDEPENDS or CURLOPTSTREAMDEPENDSE and invoking curleasyreset. An attacker can cause the application to access freed memor...

Authentication Bypass by Primary Weakness

Overview Affected versions of this package are vulnerable to Authentication Bypass by Primary Weakness in the STARTTLS process. An attacker can compromise the security of the TLS connection by exploiting a scenario where a new transfer reuses an existing live connection despite a mismatch in TLS...

Access Control Bypass

Overview Affected versions of this package are vulnerable to Access Control Bypass in the connection reuse process. An attacker can gain unauthorized access to resources or services by exploiting the reuse of an authenticated connection intended for a different service. Remediation Upgrade libcur...

Denial of Service (DoS)

Overview Affected versions of this package are vulnerable to Denial of Service DoS due to the lack of an upper bound on memory allocation for unacknowledged WebSocket PING frames. An attacker can cause memory exhaustion by sending a rapid sequence of PING messages from a malicious server. Details...

Insufficiently Protected Credentials

Overview Affected versions of this package are vulnerable to Insufficiently Protected Credentials in the Authorization header handling process. An attacker can cause sensitive authentication information to be sent to an unintended origin by reusing a handle for transfers to different HTTP origins...

Infinite loop

Overview Affected versions of this package are vulnerable to Infinite loop in the udpreceive process. An attacker can cause the client to enter a busy-loop and become unresponsive by continuously sending zero-length UDP datagrams from a malicious HTTP/3 server. Remediation Upgrade libcurl to...

Insertion of Sensitive Information Into Sent Data

Overview Affected versions of this package are vulnerable to Insertion of Sensitive Information Into Sent Data due to the improper clearing of the CURLOPTREFERER option. An attacker can cause sensitive information to be disclosed by forcing the reuse and transmission of a previous referer header ...

Use After Free

Overview Affected versions of this package are vulnerable to Use After Free in the CURLMOPTSOCKETFUNCTION callback when curleasypause is called. An attacker can execute arbitrary code or cause a denial of service by triggering the use of a dangling pointer after memory has been freed. Remediation...

Improper Verification of Cryptographic Signature

Overview Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the cookie parsing process. An attacker can cause unauthorized cookies to be set and transmitted to unrelated third-party domains by crafting HTTP responses that exploit improper doma...

Insufficiently Protected Credentials

Overview Affected versions of this package are vulnerable to Insufficiently Protected Credentials in the process that handles .netrc credential retrieval when a URL is specified with a username but without a password. An attacker can gain unauthorized access to sensitive information by exploiting...

Double Free

Overview Affected versions of this package are vulnerable to Double Free in the GSASL context cleanup process. An attacker can cause arbitrary code execution or a denial of service by triggering the double-free condition. Remediation Upgrade libcurl to version 8.21.0 or higher. References - Curl...

Improper Certificate Validation

Overview Affected versions of this package are vulnerable to Improper Certificate Validation when the CURLOPTSSLSESSIONIDCACHE is enabled and the CURLSSLOPTEARLYDATA option is set in CURLOPTSSLOPTIONS. An attacker can intercept and obtain sensitive information by impersonating a server and...

Authentication Bypass by Primary Weakness

Overview Affected versions of this package are vulnerable to Authentication Bypass by Primary Weakness due to incomplete matching of mTLS configuration options during connection reuse in the connection process. An attacker can cause connections to be reused with incorrect client certificate...

Improper Certificate Validation

Overview Affected versions of this package are vulnerable to Improper Certificate Validation in the CURLOPTSSHKEYFUNCTION process. An attacker can intercept or manipulate data by presenting a server host key type that does not match the recorded key type in the knownhosts file, which is improperl...

Access Control Bypass

Overview Affected versions of this package are vulnerable to Access Control Bypass in the process responsible for clearing proxy authentication credentials. An attacker can gain unauthorized access to sensitive proxy credentials by leveraging subsequent transfers that reuse stale authentication...

CVE-2026-9546

A vulnerability in libcurl caused the HTTP Referer: header to persist even when explicitly cleared. While the documentation states that passing NULL to CURLOPTREFERER suppresses the header, the option failed to clear the internal state. As a result the previous referrer string was erroneously...

CVE-2026-9545

In this scenario, libcurl first uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate. When libcurl returns to the hostname the second time with a cached SSL...