CVE Explorer

CVE-2026-6688

FatFs R0.16 and earlier contains a downstream-caller vulnerability pattern associated with FatFs long filename handling. With LFN enabled, fno.fname can be up to 255 characters; many callers copy it into short fixed buffers without bounds checks, causing overflow. This maps to CWE-120 (Buffer Copy without Checking Size of Input). 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). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.

Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:713b8a12ac6813f515661c0088878575a8a6542ae1149593a41394edc29bf5d2

Known exploited

Not asserted

Disputed

Stale source

Conflicts

Affected products and versions

1 source assertion

{"defaultStatus":"unaffected","product":"FatFs","vendor":"ChaN","versions":[{"lessThanOrEqual":"R0.16","status":"affected","version":"0","versionType":"custom"}]}

cve_program_cvelist_v5affected
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion

{"metric":{"attackComplexity":"LOW","attackVector":"PHYSICAL","availabilityImpact":"HIGH","baseScore":7.6,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"metric_type":"cvssV3_1"}

cve_program_cvelist_v5cvss
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

1 source assertion

{"cweId":"CWE-120","description":"CWE-120 Buffer Copy without Checking Size of Input","lang":"en","type":"CWE"}

cve_program_cvelist_v5cwe
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/problemTypes/0/descriptions/0

Source references

5 source assertions

{"tags":["product"],"url":"https://elm-chan.org/fsw/ff/"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/references/2

{"tags":["technical-description"],"url":"https://github.com/runZeroInc/vulns-2026-fatfs-chance"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/references/1

{"tags":["exploit"],"url":"https://github.com/runZeroInc/vulns-2026-fatfs-chance"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/adp/0/references/0

{"tags":["third-party-advisory"],"url":"https://www.runzero.com/advisories/fatfs-long-fn-of-downstream-cve-2026-6688/"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/references/3

{"tags":["third-party-advisory"],"url":"https://www.runzero.com/blog/fatfs-bugs/"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:8b8fc59ac91c5f8cad114e77f541ed86fafc9aacc0394c9c10b794f187808f47 · sha256:ea262a0b7df3a7e1… · /containers/cna/references/0

Attribution and limitations

CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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