CVE-2026-13215— Zephyr ext2挂载未验证块大小导致越界写入漏洞
一分钟漏洞结论
影响对象
zephyrproject zephyr
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Zephyr 操作系统的 ext2 文件系统驱动在挂载文件系统时，未能验证磁盘超级块中的 字段。 中的 函数仅校验了魔数（magic number）、版本、inode 大小和组计数，但并未对 进行边界检查。在验证通过后， 会根据攻击者可控的 32 位无符号整数 ，计算得出 。这可能导致移位溢出（产生未定义行为），或生成一个远大于 的块大小。 随后， 将该块大小传递给 ，试图从固定静态缓冲区 中分配 个块。该静态缓冲区的大小为 。然而， 并未验证请求的块是否适合该缓冲区，且 ext2 包装层丢弃了该函数的返回值，导致
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一、 漏洞 CVE-2026-13215 基础信息
漏洞信息
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Vulnerability Title
Zephyr ext2 mount: unvalidated superblock block size causes out-of-bounds write from a crafted filesystem image
来源: CVE Program / CVE List V5
Vulnerability Description
The Zephyr ext2 filesystem driver fails to validate the s_log_block_size field of the on-disk superblock when mounting a filesystem. ext2_verify_disk_superblock() in subsys/fs/ext2/ext2_impl.c checks the magic number, revision, inode size and group counts, but never bounds s_log_block_size. On a successful verify, subsys/fs/ext2/ext2_ops.c computes fs->block_size = 1024 << superblock.s_log_block_size from this attacker-controlled uint32_t, so a crafted value either overflows the shift (undefined behaviour) or yields a block size far larger than CONFIG_EXT2_MAX_BLOCK_SIZE.
That block size is then passed to k_mem_slab_init() by ext2_init_blocks_slab() to carve CONFIG_EXT2_MAX_BLOCK_COUNT blocks out of the fixed static buffer __ext2_block_memory_buffer, whose size is CONFIG_EXT2_MAX_BLOCK_COUNT * CONFIG_EXT2_MAX_BLOCK_SIZE. k_mem_slab_init() does not verify that the requested blocks fit the buffer, and the ext2 wrapper discards its return value, so the slab is laid out past the end of the static buffer. The mount immediately reads block-group, bitmap and inode blocks of fs->block_size bytes each into these slab blocks, producing an out-of-bounds write into adjacent static memory on the first block read.
The entire path is gated only by data read from the mounted image, making this reachable by any attacker who can present a crafted ext2 image to a device that mounts it (for example a removable SD card or storage medium). Because the ext2 driver runs in kernel mode, supplying image bytes yields a supervisor-mode memory-corruption primitive, with impact ranging from denial of service to potential code execution.
The fix rejects s_log_block_size values that overflow the shift (greater than 11) or that produce a block size exceeding CONFIG_EXT2_MAX_BLOCK_SIZE, so the block slab can no longer be initialized larger than its backing buffer.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
来源: CVE Program / CVE List V5
受影响产品
| 厂商 | 产品 | 影响版本 | CPE | 订阅 |
|---|---|---|---|---|
| zephyrproject | zephyr | 3.5.0 ~ 4.4.2 | - |
|
二、漏洞 CVE-2026-13215 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-13215 补丁与修复 (1)
CVE-2026-13215 厂商安全公告 (1)
IV. Related Vulnerabilities
V. Comments for CVE-2026-13215
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