libcurl 8.18.0 < 8.21.0 QUIC UDP Denial of Service (CVE-2026-11352)

The version of libcurl installed on the remote host is 8.18.0 prior to 8.21.0. It is, therefore, affected by a denial of service vulnerability: - An issue in curl's QUIC UDP receive function allows a malicious HTTP/3 server to trigger a remote denial of service against a curl or libcurl client...

CVE-2026-10536

A flaw was found in libcurl. This use-after-free vulnerability occurs when an application configures an HTTP/2 stream-dependency tree and then performs a sequence of operations involving curleasyreset and curleasycleanup. During the final cleanup, libcurl attempts to access memory that has alread...

CVE-2026-11856

A flaw was found in curl. When libcurl performs a transfer to an HTTP origin using Digest authentication and then reuses the same connection handle for a subsequent transfer to a different origin, it may incorrectly send the authentication header intended for the first origin to the second. This...

CVE-2026-11352

A flaw was found in curl and libcurl. A malicious HTTP/3 server can exploit an issue in the QUIC UDP receive function by continuously streaming empty UDP datagrams. This can lead to a remote denial of service DoS against a curl or libcurl client, as the helper function discards zero-length UDP...

CVE-2026-8932

A flaw was found in curl. The libcurl library, used for transferring data with URLs, could improperly reuse existing network connections. This occurred even when changes to mutual Transport Layer Security mTLS settings, particularly those for client certificates, should have prevented such reuse...

CVE-2026-9080

A flaw was found in libcurl. When curleasypause is called within the event-based CURLMOPTSOCKETFUNCTION callback, a use-after-free vulnerability is triggered. This occurs because libcurl attempts to store a flag using a pointer to memory that has already been freed. An attacker could potentially...

CVE-2026-9545

A flaw was found in libcurl. An attacker can exploit this by replacing a legitimate HTTP/3 server with an impostor machine. When libcurl attempts a second transfer to the same site with a cached SSL session and early data enabled, it may send sensitive request data before verifying the server's...

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...