CVE-2026-82752

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CVE-2026-82752

Summary: Ash string length constraints count graphemes, so a combining-mark string of any size passes max_length

Details: Improper Validation of Specified Quantity in Input vulnerability in ash-project ash allows an attacker to store a value of arbitrary size in an attribute whose length constraint should bound it. Ash measures string length with Elixir's String.length/1, which counts Unicode graphemes, in the max_length and min_length constraints of Ash.Type.String (apply_constraints/2 in lib/ash/type/string.ex), in Ash.Resource.Validation.StringLength, and in the string_length expression function. A grapheme carries an unbounded number of combining marks, so a base character followed by a million combining acute accents is one grapheme and megabytes of data, and satisfies max_length: 2. Where the data layer imposes no independent limit (ETS, Mnesia, or a Postgres text column) the whole value is persisted, so an attacker can write an entire request body into an attribute declared with a small maximum and grow storage without bound. The counting unit also disagrees with the storage layer, which counts codepoints rather than graphemes, so a value accepted by the constraint can still be rejected or truncated by the column. A Postgres varchar(n) column bounds the value itself and is not exposed. This issue affects ash: from 0.10.0 before 3.33.0.

References: https://cna.erlef.org/cves/CVE-2026-82752.html, https://github.com, https://osv.dev/vulnerability/EEF-CVE-2026-82752, https://repo.hex.pm, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82752.json, https://github.com/ash-project/ash/security/advisories/GHSA-cwjv-574p-59f6, https://nvd.nist.gov/vuln/detail/CVE-2026-82752, https://github.com/ash-project/ash/commit/a64cab49b8886503e6b7c7b211d83c475aac48ca, https://github.com/ash-project/ash/commit/cdbf4c4da6bda5f6f139078f01a64320b595216d, https://github.com/ash-project/ash