GHSA-X5M4-43JF-HH65
Vulnerability from github – Published: 2026-01-28 16:18 – Updated: 2026-01-28 16:18Impact
Incorrect rounding direction for signed mul and div operations
The mulDiv(x, y, z) function incorrectly handled cases where both the intermediate product $x * y$ and the divisor $z$ were negative. The logic assumed that if the intermediate product was negative, the final result must also be negative, neglecting the sign of $z$.
This resulted in rounding being applied in the wrong direction for cases where both $x * y$ and $z$ were negative. The functions most at risk are fixed_div_floor and fixed_div_ceil, as they often use non-constant numbers as the divisor $z$ in mulDiv.
This error is present in all signed FixedPoint and SorobanFixedPoint implementations, including i64, i128, and I256.
Negative Overflow in i64
The mulDiv(x, y, z) function for i64 used the i128 type to handle "phantom overflows". These are overflows that occur intermediately during a calculation, like when computing the intermediate product $x * y$. When the final result of mulDiv was computed in i128, it was scaled back down to i64 before returning. While the code verified that the result did not exceed i64::MAX, it did not check against i64::MIN.
This caused negative results smaller than i64:MIN to wrap around to a large positive number instead of being caught as an overflow.
This error only exists for the FixedPoint implementation of i64.
Patches
- v1.3.0 users should upgrade to patch v1.3.1
- v1.4.0 users should upgrade to patch v1.4.1
All versions >=v1.4.1 contain the patch.
Workarounds
There are no known workarounds. Upgrade to the patched version.
Credits
soroban-fixed-point-math would like to thank the team at Certora for discovering and reporting the issue.
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "soroban-fixed-point-math"
},
"ranges": [
{
"events": [
{
"introduced": "1.4.0"
},
{
"fixed": "1.4.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.4.0"
]
},
{
"package": {
"ecosystem": "crates.io",
"name": "soroban-fixed-point-math"
},
"ranges": [
{
"events": [
{
"introduced": "1.3.0"
},
{
"fixed": "1.3.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.3.0"
]
}
],
"aliases": [
"CVE-2026-24783"
],
"database_specific": {
"cwe_ids": [
"CWE-682"
],
"github_reviewed": true,
"github_reviewed_at": "2026-01-28T16:18:54Z",
"nvd_published_at": "2026-01-27T22:15:57Z",
"severity": "HIGH"
},
"details": "### Impact\n\n#### Incorrect rounding direction for signed mul and div operations\n\nThe `mulDiv(x, y, z)` function incorrectly handled cases where both the intermediate product $x * y$ and the divisor $z$ were negative. The logic assumed that if the intermediate product was negative, the final result must also be negative, neglecting the sign of $z$.\n\nThis resulted in rounding being applied in the wrong direction for cases where both $x * y$ and $z$ were negative. The functions most at risk are `fixed_div_floor` and `fixed_div_ceil`, as they often use non-constant numbers as the divisor $z$ in `mulDiv`. \n\nThis error is present in all signed `FixedPoint` and `SorobanFixedPoint` implementations, including `i64`, `i128`, and `I256`.\n\n#### Negative Overflow in `i64`\n\nThe `mulDiv(x, y, z)` function for `i64` used the `i128` type to handle \"phantom overflows\". These are overflows that occur intermediately during a calculation, like when computing the intermediate product $x * y$. When the final result of `mulDiv` was computed in `i128`, it was scaled back down to `i64` before returning. While the code verified that the result did not exceed `i64::MAX`, it did not check against `i64::MIN`.\n\nThis caused negative results smaller than `i64:MIN` to wrap around to a large positive number instead of being caught as an overflow.\n\nThis error only exists for the `FixedPoint` implementation of `i64`. \n\n### Patches\n\n* v1.3.0 users should upgrade to patch v1.3.1\n* v1.4.0 users should upgrade to patch v1.4.1\n\nAll versions `\u003e=v1.4.1` contain the patch. \n\n### Workarounds\nThere are no known workarounds. Upgrade to the patched version.\n\n### Credits\n\nsoroban-fixed-point-math would like to thank the team at [Certora](https://www.certora.com/) for discovering and reporting the issue.",
"id": "GHSA-x5m4-43jf-hh65",
"modified": "2026-01-28T16:18:54Z",
"published": "2026-01-28T16:18:54Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/script3/soroban-fixed-point-math/security/advisories/GHSA-x5m4-43jf-hh65"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24783"
},
{
"type": "WEB",
"url": "https://github.com/script3/soroban-fixed-point-math/commit/c9233f7094198a49ed66a4d75786a8a3755c936a"
},
{
"type": "PACKAGE",
"url": "https://github.com/script3/soroban-fixed-point-math"
},
{
"type": "WEB",
"url": "https://github.com/script3/soroban-fixed-point-math/releases/tag/v1.3.1"
},
{
"type": "WEB",
"url": "https://github.com/script3/soroban-fixed-point-math/releases/tag/v1.4.1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "soroban-fixed-point-math has Incorrect Rounding and Overflow Handling in Signed Fixed-Point Math with Negatives"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.