CVE-2026-55209
resdata insufficiently validates untrusted GRDECL files
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
9.8
resdata insufficiently validates untrusted GRDECL files
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.
- Record
CVE-2026-55209- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-120, CWE-125, CWE-129, CWE-476
- Updated
- 2026-11-02
EUVDEUVD-2026-77802
9.8
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.
- Record
EUVD-2026-77802- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-pr85-w493-9w3x
9.8
resdata has Classic Buffer Overflow, Improper Validation of Array Index, NULL Pointer Dereference and Out-of-bounds Read
Impact
Prior to version 6.2.9 resdata would not correctly validate input in GRDECL files. The severity rating assumes that resdata is used to parse untrused files in a networking context such as a webservice.
Patches
The bug has been patched starting with version 6.2.9.
- Record
GHSA-pr85-w493-9w3x- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-120, CWE-125, CWE-129, CWE-476
- Updated
- 2026-11-02
NVD
9.8
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.
- Record
CVE-2026-55209- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-120, CWE-125, CWE-129, CWE-476
- Updated
- 2026-11-02
OSV
9.8
resdata insufficiently validates untrusted GRDECL files
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.
- Record
CVE-2026-55209- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-120, CWE-125, CWE-129, CWE-476
- Updated
- 2026-11-02
OSVGHSA-pr85-w493-9w3x
9.8
resdata has Classic Buffer Overflow, Improper Validation of Array Index, NULL Pointer Dereference and Out-of-bounds Read
Impact
Prior to version 6.2.9 resdata would not correctly validate input in GRDECL files. The severity rating assumes that resdata is used to parse untrused files in a networking context such as a webservice.
Patches
The bug has been patched starting with version 6.2.9.
- Record
GHSA-pr85-w493-9w3x- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-120, CWE-125, CWE-129, CWE-476
- Updated
- 2026-11-02
OSVPYSEC-2026-3694
9.8
resdata has Classic Buffer Overflow, Improper Validation of Array Index, NULL Pointer Dereference and Out-of-bounds Read
Impact
Prior to version 6.2.9 resdata would not correctly validate input in GRDECL files. The severity rating assumes that resdata is used to parse untrused files in a networking context such as a webservice.
Patches
The bug has been patched starting with version 6.2.9.
- Record
PYSEC-2026-3694- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-55209 is a critical vulnerability (CVSS 9.8) in Equinor Resdata, published August 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.78%, the 56th percentile. Fixed in resdata 6.2.9.
References
github.com/equinor/resdata/security/advisories/GHSA-pr85-w493-9w3x
github.com/equinor/resdata/pull/1166
github.com/equinor/resdata/commit/9f8fd6db472e0696080b768389914d60a453904f
github.com/equinor/resdata/commit/d3f45828e9413506b8e8160a9304f4b7b06dcefc
github.com/equinor/resdata/commit/ee8cc12b026d945df3077bc98e211ee45f80a433
github.com/equinor/resdata/releases/tag/6.2.9