hsec-2026-0012
osv_haskell# Out-of-bounds read in Eq and Ord on numbers with extreme exponents `scientific-0.3.9.0` reimplemented `Eq` and `Ord` without normalising their arguments. The new implementation short-circuits on `integerLog10' c + e` computed in `Int`, which overflows when the base-10 exponent is close to `maxBound :: Int`. The overflowed comparison then falls through to `magnitude (e1 - e2)`, where the exponent difference overflows to a negative `Int` as well. `magnitude` indexed its cached power-of-ten array without a bounds check, so the negative index performed an out-of-bounds read and the process died with `SIGSEGV`. With `scientific-0.3.9.0` (GHC 9.10.3, x86_64-linux), as reported in [basvandijk/scientific#120](https://github.com/basvandijk/scientific/issues/120): ```haskell import Data.Scientific main :: IO () main = print (scientific 10 maxBound == scientific 1 minBound) ``` ``` $ ./repro; echo "exit=$?" exit=139 ``` The issue was discovered when Stackage nightly test suites (`genvalidity-hspec-aeson`, `genvalidity-sydtest-aeson`) started segfaulting after upgrading to `scientific-0.3.9.0`: their property tests round-trip `aeson` `Value`s, which produces `Scientific`s with extreme exponents. Versions before `0.3.9.0` did not crash, but `Eq`/`Ord` returned invalid results there instead (the normalisation-based implementation overflows the exponent, reporting `scientific 10 maxBound == scientific 1 minBound` as `True`). The same unchecked read was also reachable through `(+)` and `(-)` on older versions, guarded only by the documented warning about the potential `10^e` blowup — reading outside the cache is not. ## Resolution `scientific-0.3.10.0` computes the logarithms using `Integer`, fixing both the crash and the invalid comparison results, and bounds-checks `magnitude`, so a negative exponent now raises an error instead of reading out of bounds. All entry points (`Eq`, `Ord`, `(+)`, `(-)`) are covered; upgrade to `scientific-0.3.10.0` or later. Note that printing values with exponents close to `maxBound :: Int` remains unreliable due to the inherent `Int` exponent overflow in `normalize`; this limitation is documented upstream and postponed to the next major release. ## Credits Reported by Tom Sydney Kerckhove (@NorfairKing); fixed by Oleg Grenrus (@phadej).
- Published
- unknown
- Last Modified
- unknown
CVSS details not available.
No product information available.
No linked vulnerabilities found.
{
"affected": [
{
"database_specific": {
"human_link": "https://github.com/haskell/security-advisories/tree/main/advisories/published/2026/HSEC-2026-0012.md",
"osv": "https://raw.githubusercontent.com/haskell/security-advisories/refs/heads/generated/osv-export/2026/HSEC-2026-0012.json",
"source": "https://github.com/haskell/security-advisories/blob/generated/osv-export/2026/HSEC-2026-0012.json"
},
"package": {
"ecosystem": "Hackage",
"name": "scientific",
"purl": "pkg:hackage/scientific"
},
"ranges": [
{
"events": [
{
"introduced": "0.3.9.0"
},
{
"fixed": "0.3.10.0"
}
],
"type": "ECOSYSTEM"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"type": "CVSS_V3"
}
],
"versions": [
"0.3.9.0"
]
}
],
"database_specific": {
"home": "https://github.com/haskell/security-advisories",
"osvs": "https://raw.githubusercontent.com/haskell/security-advisories/refs/heads/generated/osv-export",
"repository": "https://github.com/haskell/security-advisories"
},
"details": "# Out-of-bounds read in Eq and Ord on numbers with extreme exponents\n\n`scientific-0.3.9.0` reimplemented `Eq` and `Ord` without normalising their\narguments. The new implementation short-circuits on\n`integerLog10' c + e` computed in `Int`, which overflows when the base-10\nexponent is close to `maxBound :: Int`. The overflowed comparison then falls\nthrough to `magnitude (e1 - e2)`, where the exponent difference overflows to a\nnegative `Int` as well. `magnitude` indexed its cached power-of-ten array\nwithout a bounds check, so the negative index performed an out-of-bounds read\nand the process died with `SIGSEGV`.\n\nWith `scientific-0.3.9.0` (GHC 9.10.3, x86_64-linux), as reported in\n[basvandijk/scientific#120](https://github.com/basvandijk/scientific/issues/120):\n\n```haskell\nimport Data.Scientific\n\nmain :: IO ()\nmain = print (scientific 10 maxBound == scientific 1 minBound)\n```\n\n```\n$ ./repro; echo \"exit=$?\"\nexit=139\n```\n\nThe issue was discovered when Stackage nightly test suites\n(`genvalidity-hspec-aeson`, `genvalidity-sydtest-aeson`) started segfaulting\nafter upgrading to `scientific-0.3.9.0`: their property tests round-trip\n`aeson` `Value`s, which produces `Scientific`s with extreme exponents.\n\nVersions before `0.3.9.0` did not crash, but `Eq`/`Ord` returned invalid\nresults there instead (the normalisation-based implementation overflows the\nexponent, reporting `scientific 10 maxBound == scientific 1 minBound` as\n`True`). The same unchecked read was also reachable through `(+)` and `(-)` on\nolder versions, guarded only by the documented warning about the potential\n`10^e` blowup — reading outside the cache is not.\n\n## Resolution\n\n`scientific-0.3.10.0` computes the logarithms using `Integer`, fixing both the\ncrash and the invalid comparison results, and bounds-checks `magnitude`, so a\nnegative exponent now raises an error instead of reading out of bounds. All\nentry points (`Eq`, `Ord`, `(+)`, `(-)`) are covered; upgrade to\n`scientific-0.3.10.0` or later.\n\nNote that printing values with exponents close to `maxBound :: Int` remains\nunreliable due to the inherent `Int` exponent overflow in `normalize`; this\nlimitation is documented upstream and postponed to the next major release.\n\n## Credits\n\nReported by Tom Sydney Kerckhove (@NorfairKing); fixed by Oleg Grenrus\n(@phadej).\n",
"id": "HSEC-2026-0012",
"modified": "2026-11-03T22:45:02.613041440Z",
"published": "2026-11-03T22:32:58Z",
"references": [
{
"type": "REPORT",
"url": "https://github.com/basvandijk/scientific/issues/120"
},
{
"type": "REPORT",
"url": "https://github.com/NorfairKing/validity/issues/121"
},
{
"type": "FIX",
"url": "https://github.com/basvandijk/scientific/pull/121"
},
{
"type": "DISCUSSION",
"url": "https://www.reddit.com/r/haskell/comments/1xbj59g/dont_use_scientific_for_calculations_it_can/"
}
],
"related": [
"HSEC-2026-0011"
],
"schema_version": "1.9.2",
"summary": "Out-of-bounds read in Eq and Ord on numbers with extreme exponents"
}