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Vulnerability record · CVE-2026-6682 · published 1 July 2026

CVE-2026-6682: Elm-chan fatfs integer overflow vulnerability

Elm Chan · Fatfs

In FatFS R0.16 and earlier contains a FAT32 integer overflow bug in mount_volume() where fasize *= fs->n_fats can wrap, leading to attacker-controlled file-size metadata and unsafe read lengths in downstream callers. This maps to CWE-190 (Integer Overflow or Wraparound). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). Remote delivery is also possible in OTA/update pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.

7.6 CVSS 3.1 High EPSS 0.32% · top 77.3% CWE-190 · Integer overflow
7.6CVSS 3.1 base score
0.32%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References, 4 tagged exploit
2 Jul 2026Last modified by NVD

Description

In FatFS R0.16 and earlier contains a FAT32 integer overflow bug in mount_volume() where fasize *= fs->n_fats can wrap, leading to attacker-controlled file-size metadata and unsafe read lengths in downstream callers. This maps to CWE-190 (Integer Overflow or Wraparound). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). Remote delivery is also possible in OTA/update pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://elm-chan.org/fsw/ff/ Product
https://github.com/runZeroInc/vulns-2026-fatfs-chance Third Party AdvisoryExploit
https://www.runzero.com/advisories/fatfs-fat32-int-of-mnt-cve-2026-6682/ Third Party AdvisoryExploit
https://www.runzero.com/blog/fatfs-bugs/ Third Party AdvisoryExploit
https://github.com/runZeroInc/vulns-2026-fatfs-chance Third Party AdvisoryExploit

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.6CVE-2026-6688Elm-chan fatfs classic buffer overflow vulnerabilityFatFs R0.16 and earlier contains a downstream-caller vulnerability pattern associated with FatFs long filename handling. With LFN enabled, fno.fname …EPSS 0.32%7.6CVE-2026-6687Elm-chan fatfs stack-based buffer overflow vulnerabilityFatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec ma…EPSS 0.35%4.6CVE-2026-6683Elm-chan fatfs divide by zero vulnerabilityFatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync oper…EPSS 0.31%4.6CVE-2026-6684Elm-chan fatfs vulnerabilityFatFs prior to R0.16 that use GPT scanning with 'FF_LBA64 = 1' contains an issue where an unbounded loop count derived from GPT header field GPTH_PtN…EPSS 0.31%4.6CVE-2026-6686Elm-chan fatfs use of uninitialized resource vulnerabilityFatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clust…EPSS 0.26%8.4CVE-2025-48595Android Framework integer overflow enables local code executionAn integer overflow in multiple locations of the Android Framework can be turned into code execution. It allows a local attacker to escalate privileg…KEVEPSS 1.7%analysed7.8CVE-2021-30952Apple WebKit integer overflow allows code execution via crafted web contentAn integer overflow in Apple's WebKit engine was fixed by improved input validation across tvOS 15.2, macOS Monterey 12.1, Safari 15.2, iOS/iPadOS 15…KEVEPSS 7.0%analysed7.8CVE-2026-21385Qualcomm chipset firmware memory corruption via alignment integer overflowA memory corruption flaw in Qualcomm chipset firmware arises from an integer overflow when alignments are used for memory allocation (CWE-190). It af…KEVEPSS 1.2%analysed

Source: NIST National Vulnerability Database (record CVE-2026-6682), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.