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Power Open Source Development

Explore the open source tools and capabilities for building and deploying modern applications on IBM Power platforms including AIX, IBM i, and Linux.


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  • 1.  libssh2 security vulnerability fix

    Posted 07/28/26 12:57 AM

    good morning,

    our security team informed us about a security vulnerability fix in libssh2

    Description
    libssh2 is a C library for providing SSH2 services on both the client and server sides. It can be used to run programs remotely, transfer files, or as a secure and transparent tunnel for remote programs.

    CVE-2026-66034
    A vulnerability exists in libssh2. A missing scope check in the public key subsystem allows a malicious SSH server to initiate an out-of-scope read request and release an uninitialized pointer.
     
    A remote, anonymous attacker could exploit this vulnerability to potentially disclose sensitive information, cause a denial-of-service condition, or execute arbitrary code. Successful exploitation requires user action.
    CVE-2026-66035
    There is a vulnerability in libssh2. A heap buffer overflow in the `fullpacket()` function allows a malicious SSH server to corrupt the heap memory by sending a packet whose length is smaller than the negotiated Encrypt-then-MAC (ETM) cipher block size. A remote, anonymous attacker can exploit this vulnerability to potentially cause a denial-of-service condition or execute arbitrary code. Successful exploitation requires user action.
    Please provide the appropriate patches.


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    Stefan Martin
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  • 2.  RE: libssh2 security vulnerability fix

    Posted 12 days ago

    Hallo there,

    I haven't seen any reaction to this entry in two months hence I am curious. It would be great if sbdy from the toolbox dev team could either comment on why libssh2 CVE-2026-55200 with CVSS 9.8 is not a problem for the toolbox libssh2-1.11.1-1.ppc or when the fix is going to be available.

    Thanks and regards,

    Andreas Schulze



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    Andreas Schulze
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  • 3.  RE: libssh2 security vulnerability fix

    Posted 12 days ago

    We are working on this.
    We were waiting for the libssh2 community to release a new version, but no release yet. There are multiple security vulnerabilities accumulated in the last released version. Backporting fixes for all of them is going to be challenging. So the plan is to identify the critical ones and update accordingly. It will updated soon in AIX Toolbox. 



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    Ayappan P
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