Bug 2563613 (CVE-2026-118769)

Summary:	CVE-2026-118769 botan: Botan: Integer overflow when reporting block size in FFI can cause memory corruption
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	dschmidt, jlanda, kshier, rbobbitt, rhel-process-autobot, simaishi, stcannon, watson-tool-maintainers, yguenane
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Botan. An attacker can exploit an unchecked integer truncation in the C programming interface by supplying untrusted algorithm parameters that specify a variable-block-size cipher. This flaw causes the application to allocate an undersized memory buffer, resulting in heap memory corruption during data processing that may lead to arbitrary code execution or a denial of service (DoS).	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2565382, 2565383, 2565385, 2565386
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Description OSIDB Bzimport 2026-10-29 18:23:32 UTC

Botan is a C++ cryptography library. From 2.1.0 until 3.13.0, the Botan C API function botan_block_cipher_block_size converted a size_t block size to int without a bounds check. In an application that accepts external algorithm parameter strings and uses the FFI raw ECB mode, an attacker can select the variable-block-size Lion cipher so that the reported size is truncated, the caller allocates insufficient memory, and later block processing causes memory corruption. The C++ API and normally used C API modes such as CBC and CTR are unaffected. This issue is fixed in version 3.13.0.