Description

resdata is software for reading and writing result files from the Eclipse reservoir simulator. Prior to 6.2.9, resdata insufficiently validates numeric fields, grid dimensions, keyword sizes, and array indexes while parsing untrusted GRDECL files in lib/resdata/rd_kw_grdecl.cpp and lib/resdata/rd_grid.cpp. Malformed COORD, ZCORN, CORSNUM, ACTNUM, or MAPAXES data can reach rd_grid_alloc_GRDECL_kw__ with inconsistent lengths, while unbounded floating-point conversion can exceed the intended parser buffer. In a network service that accepts untrusted GRDECL files, these conditions can cause a classic buffer overflow, out-of-bounds reads, invalid array access, NULL pointer dereference, memory corruption, or service termination. This issue is fixed in version 6.2.9.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-09-14T20:16:47.487Z",
  "pubdate": "2026-09-14T20:16:47.487Z",
  "executiveSummary": "The resdata library, used by the Eclipse reservoir simulator, contains critical input validation flaws in its handling of GRDECL files. Prior to version 6.2.9, the software fails to properly sanitize numeric fields, grid dimensions, keyword sizes, and array indexes during the parsing process. This oversight allows maliciously crafted input—specifically within COORD, ZCORN, CORSNUM, ACTNUM, or MAPAXES data—to trigger various memory safety violations.\nThe vulnerability manifests as buffer overflows, out-of-bounds read/write operations, invalid array indexing, and NULL pointer dereferences. These flaws present a significant security risk, potentially leading to arbitrary code execution, denial-of-service, or memory corruption. The vulnerability is particularly dangerous in network-exposed services that process untrusted GRDECL files, as an unauthenticated attacker could remotely trigger these conditions. Successful exploitation requires the application to accept and parse maliciously formatted reservoir data files. Users are advised to upgrade to version 6.2.9 or later to remediate these issues.",
  "technicalDetails": "The vulnerability resides within the parsing logic located in lib/resdata/rd_kw_grdecl.cpp and lib/resdata/rd_grid.cpp. The core issue is an insufficient validation mechanism during the ingestion of GRDECL files. When the parser encounters keywords such as COORD, ZCORN, CORSNUM, ACTNUM, or MAPAXES, it fails to verify that the provided numeric fields and array dimensions align with the internal memory allocations expected by the system.\nSpecifically, when malformed data is processed, it is passed to the rd_grid_alloc_GRDECL_kw__ function with inconsistent length parameters. Because the parser performs unbounded floating-point conversions, it can exceed the allocated buffer size, resulting in a heap-based or stack-based buffer overflow. Furthermore, the lack of boundary checking on array indexes allows for out-of-bounds memory access, which can result in the disclosure of sensitive memory contents or the corruption of function pointers and control data structures.\nThe attack flow proceeds as follows: An attacker submits a malicious GRDECL file to a network service utilizing the resdata library. As the parser iterates through the file, it reads the untrusted dimensions and coordinate values. Because the parser does not enforce strict size constraints or validate that the provided values match the expected structure of the grid, the input triggers memory allocation routines with insufficient space. The subsequent write operation spills over into adjacent memory regions. Depending on the memory layout and the nature of the overflow, the attacker may achieve controlled memory corruption. In instances where index values are manipulated, the parser may attempt to dereference a NULL pointer or access memory addresses outside of valid heap bounds, leading to service termination (Denial of Service).\nAffected versions include all resdata versions prior to 6.2.9. The vulnerability is exploitable without authentication, provided the service is configured to process external GRDECL files. The impact of successful exploitation ranges from process crashes to the potential for arbitrary code execution if the attacker successfully overwrites critical application state or return addresses in memory. The primary weakness is the implicit trust placed in the dimensions and data values defined within the untrusted input files, bypassing existing security boundaries during the allocation phase."
}