F´: File size bounds bypass in Svc::FileUplink via unsigned integer overflow in DATA packet validation

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

F´ (F Prime) is a framework that enables development and deployment of spaceflight and other embedded software applications. Prior to 4.2.0, Svc::FileUplink handleDataPacket offset and size validation is vulnerable because the component checks byteOffset plus dataSize with wrapping U32 arithmetic and then seeks to the large attacker-controlled offset before writing. When a file-uplink DATA packet supplies a byteOffset and dataSize whose unsigned sum wraps below the declared file size, data can be written beyond the declared upload size, causing file integrity loss and potentially large sparse-file growth or resource exhaustion. This issue is fixed in version 4.2.0.

Source published

14 Oct 2026 17:17:20 UTC

Source modified

15 Oct 2026 18:55:39 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H