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RCE in SzafirHost native library archive verification

IdentifiersCVE-2026-13165CWE-434

CVE-2026-13165 is a remote code execution vulnerability in Krajowa Izba Rozliczeniowa's SzafirHost affecting versions prior to 1.2.2. The flaw is caused by inconsistent parsing of downloaded signed native library archives: SzafirHost verifies the archive with a JarFile parser that reads the ZIP/JAR Central Directory, but extracts native libraries with JarInputStream, which processes entries sequentially from local file headers. An attacker who controls the served archive can append or insert a malicious native library entry (DLL, SO, or DYLIB) as a local-file-header entry between the last legitimate file and the Central Directory without listing it in the Central Directory. Because the verifier only inspects Central Directory entries, it does not see the injected file and accepts the archive as validly signed. The extractor, however, reads the hidden entry sequentially and writes the attacker-controlled library into the native temporary directory without an additional hash check. This parser differential allows a malicious native library to bypass signature verification and be loaded, leading to code execution.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an attacker to bypass archive signature verification for downloaded native libraries and cause extraction of an attacker-controlled DLL, SO, or DYLIB to the native temporary directory. Because the injected library is treated as part of a trusted signed archive, exploitation can result in remote code execution in the context of the affected SzafirHost process or host environment.

Mitigation

If you can’t patch tonight, do this now.

If immediate upgrade is not possible, reduce exposure by ensuring native library archives are obtained only from fully trusted, authenticated sources under strict transport and origin control, and by independently validating archive contents before extraction. Review and harden native library extraction workflows so that only entries present in the verified Central Directory are extracted, and add explicit integrity or hash verification for extracted native libraries. These are compensating controls only; the primary mitigation is upgrading to 1.2.2 or later.

Remediation

Patch, then assume compromise.

Upgrade SzafirHost to version 1.2.2 or later. The fix addresses the inconsistency between archive verification and extraction logic. Archive validation and extraction should be performed over the same canonical set of entries, and extracted native libraries should be subject to integrity verification rather than relying solely on Central Directory-based signature checks.
PUBLIC EXPLOITS

Exploits

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