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CVE-2026-118769— Botan: Integer overflow when reporting block size in FFI can cause memory corruption

Quick assessment

Affected
randombit botan
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Botan 是一个 C++ 密码学库。在 2.1.0 至 3.13.0 版本中，Botan 的 C API 函数 在将 类型的块大小转换为 时未进行边界检查。如果应用程序接受外部算法参数字符串并使用 FFI 原始 ECB 模式，攻击者可以选择可变块大小的 Lion 密码算法，导致报告的块大小被截断；调用方因此分配了不足的内存，随后在处理数据块时引发内存破坏。该问题不影响 C++ API，也不影响通常使用的 C API 模式（如 CBC 和 CTR）。此问题已在 3.13.0 版本中修复。

CVSS 9.2 · Critical

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
randombit botan >= 2.1.0, < 3.13.0 affected
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I. Basic Information for CVE-2026-118769

Vulnerability Information
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Vulnerability Title
Botan: Integer overflow when reporting block size in FFI can cause memory corruption
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
randombit botan >= 2.1.0, < 3.13.0 -

II. Public POCs for CVE-2026-118769

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III. Intelligence Information for CVE-2026-118769

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Other References for CVE-2026-118769 (3)

Same Patch Batch · randombit · 2026-10-29 · 5 CVEs total

CVE-2026-118765 7.3 HIGH Botan: AutoSeeded_RNG can become reinitialized from predictable data after clearing state
CVE-2026-118766 6.1 MEDIUM Botan: Online OCSP redirects enable blind requests to internal HTTP services
CVE-2026-118768 5.9 MEDIUM Botan: CLI utility `ocsp_check` accepts unauthenticated responses
CVE-2026-118767 4.8 MEDIUM Botan: Python binding bcrypt APIs truncate passwords containing embedded NULs

IV. Related Vulnerabilities

Same product: botan
Same vendor: randombit
Same weakness: CWE-125