CVE-2026-13478— Zephyr ext2 块位图验证越界读取漏洞
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。
以下是该漏洞描述信息的中文翻译： Zephyr 的 ext2 文件系统驱动在 函数中（位于 ）通过计算 并将结果传递给 来验证磁盘上的块位图（block bitmap）。然而，该辅助函数（位于 ）将其参数视为位的数量，并以每 8 位读取一个字节的方式处理位图。实际上，位图缓冲区（ ）仅是一个获取的磁盘块，大小仅为 字节（即最多 位）。 和 直接从超级块中获取，且未与该单组的容量上限进行边界检查。 仅验证魔数（magic）、修订版本（revision）和块大小移位（block-size shift），但未对块计数进行
影响版本矩阵 1
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| zephyrproject | zephyr | 3.5.0< 4.4.2 |
affected |
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一、 漏洞 CVE-2026-13478 基础信息
漏洞信息
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Vulnerability Title
Out-of-bounds read in Zephyr ext2 block-bitmap validation from a crafted s_blocks_count
来源: CVE Program / CVE List V5
Vulnerability Description
The Zephyr ext2 filesystem driver validates the on-disk block bitmap in ext2_init_fs() (subsys/fs/ext2/ext2_impl.c) by passing fs_blocks = s_blocks_count - s_first_data_block to ext2_bitmap_count_set(). That helper (subsys/fs/ext2/ext2_bitmap.c) treats its argument as a number of bits and reads one bitmap byte per eight bits, but the bitmap buffer (BGROUP_BLOCK_BITMAP) is a single fetched block of only fs->block_size bytes (capacity fs->block_size * 8 bits). s_blocks_count and s_first_data_block are taken verbatim from the superblock and were never bounded against this single-group capacity; ext2_verify_disk_superblock() checks the magic, revision, and block-size shift but not the block count.
A crafted ext2 image with an oversized s_blocks_count (up to ~4 billion, against a maximum 4096-byte block / 32768-bit bitmap) makes ext2_bitmap_count_set() scan roughly 512 MB of memory past the bitmap block — a large out-of-bounds read of the static block slab and adjacent memory.
The defect is reached during mount: ext2_init_fs() is invoked from ext2_mount() (subsys/fs/ext2/ext2_ops.c), the registered .mount operation. Any path that mounts an attacker-supplied ext2 image (removable media, a disk/flash partition, or a downloaded image) triggers it. The kernel-privileged parser operates on attacker-controlled data, so the bug is exploitable wherever untrusted ext2 media can be mounted.
Impact is an out-of-bounds read only: the resulting bit count is compared internally and the mount is rejected, so no attacker-controlled bytes are returned (not a useful information leak). The ~512 MB over-read will almost certainly cross an unmapped or MPU-protected boundary and fault, crashing the system — a denial of service triggered by mounting a single malformed image. The fix rejects any image whose fs_blocks exceeds fs->block_size * 8 before the scan.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
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-2026-13478 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-13478 补丁与修复 (1)
CVE-2026-13478 厂商安全公告 (1)
同批安全公告 · zephyrproject · 2026-08-25 · 共 5 条
| CVE-2026-13214 | 9.8 CRITICAL | OCPP GetConfiguration密钥解析栈缓冲区溢出漏洞 |
| CVE-2026-13215 | 6.8 MEDIUM | Zephyr ext2挂载未验证块大小导致越界写入漏洞 |
| CVE-2026-13216 | 6.1 MEDIUM | Zephyr virtio PCI驱动越界栈写入漏洞 |
| CVE-2026-13217 | 5.9 MEDIUM | Zephyr OCPP CALLRESULT解析空指针解引用漏洞 |
IV. Related Vulnerabilities
V. Comments for CVE-2026-13478
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