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6a20a83421
The initial CVE-2026-6682 fix (merged in !50362) hardened the exFAT mount path, but the CVE as reported by runZero is a FAT32 defect in mount_volume() and is reachable in ESP-IDF's default configuration (exFAT and 64-bit LBA disabled). This corrects the fix. Root cause: `fasize *= fs->n_fats` is a DWORD multiply with no overflow guard. A crafted BPB_FATSz32 such as 0x80000001 with NumFATs=2 wraps `fasize` to 0x00000002. The wrapped (too-small) FAT size then places `fs->database` inside the FAT region, so a forged directory entry in the overlapping sector yields an attacker-controlled `finfo.fsize`. Any caller that uses that size as a read length overflows its buffer with attacker-controlled bytes (CVSS 7.6, path to RCE). The later `fs->fsize < szbfat` check does not catch this because it compares the un-doubled single-FAT size, which is still large. Fix: reject a per-FAT size that overflows DWORD when multiplied by the FAT count, and reject a reserved+FAT+root system-area size that overflows DWORD, before either value is used to derive the data-area base. The previous exFAT cluster-heap/bitmap 64-bit promotions are retained as defense-in-depth and their comments relabeled accordingly (they are not CVE-2026-6682). The SBOM cve-exclude-list reason is updated to describe the FAT32 overflow and its fix.
21 lines
1.7 KiB
YAML
21 lines
1.7 KiB
YAML
name: 'FatFs'
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version: 'R0.16'
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supplier: 'Organization: Espressif Systems (Shanghai) CO LTD'
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originator: 'Person: ChaN'
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description: 'Generic FAT Filesystem Module for embedded systems.'
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cve-exclude-list:
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- cve: CVE-2026-6682
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reason: FAT32 integer overflow in mount_volume(). Patched by rejecting per-FAT and system-area sizes that overflow the 32-bit multiply before use; the exFAT cluster-heap/bitmap multiplies were additionally widened to 64-bit as defense-in-depth.
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- cve: CVE-2026-6683
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reason: exFAT divide-by-zero when NumClusters == 0. Patched by rejecting an empty cluster heap at mount and guarding the divisor (n_fatent > 2) in sync_fs().
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- cve: CVE-2026-6685
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reason: Unsigned-subtraction wrap in the dirty-cache refill check. Patched by requiring the cached sector to lie within the direct-I/O range in both f_write() and f_read().
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- cve: CVE-2026-6687
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reason: exFAT label-length overflow in f_getlabel(). Patched by clamping XDIR_NumLabel to the 11-unit exFAT label maximum.
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- cve: CVE-2026-6684
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reason: GPT partition-scan loop DoS. Already fixed upstream in FatFs R0.16, where test_gpt_header() caps the partition-entry count at 128.
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- cve: CVE-2026-6686
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reason: Read of uninitialized clusters after f_lseek() extends a file past EOF. Longstanding FatFs behavior; not a memory-safety defect and zero-filling every extended cluster is prohibitively costly on flash. Applications sharing media across trust boundaries must zero regions before exposing them.
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- cve: CVE-2026-6688
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reason: Long-filename overflow in downstream callers copying FILINFO.fname. Not exposed in ESP-IDF; vfs_fat.c uses bounded snprintf/strlcpy and fname is bounded in-library by FF_MAX_LFN.
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