Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2025-21789 is a high-severity Out-of-bounds Read (CWE-125) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 13th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2025-21789 is a vulnerability in the Linux kernel's LoongArch architecture implementation of IP checksum calculation. It manifests as an out-of-bounds read and undefined shift operation triggered by negative lengths, stemming from commit 69e3a6aa6be2 ("LoongArch: Add checksum optimization for 64-bit system"). This issue mirrors a previously fixed problem in ARM64 via commit 8bd795fedb84. The flaw is classified under CWE-125 (Out-of-bounds Read) with a CVSS v3.1 base score of 7.1 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H).
A local attacker with low privileges can exploit this vulnerability with low attack complexity and no user interaction required. Successful exploitation enables high-impact confidentiality violations through out-of-bounds reads, potentially leaking sensitive kernel memory, alongside high availability disruption, such as denial of service via crashes or instability.
Mitigation is provided through upstream kernel patches in the stable repository, including commits 6287f1a8c16138c2ec750953e35039634018c84a, 964a8895704a22efc06a2a3276b624a5ae985a06, 9f15a8df542c0f08732a67d1a14ee7c22948fb97, and d6508ffff32b44b6d0de06704034e4eef1c307a7. Security practitioners should update affected LoongArch-based Linux kernels to incorporate these fixes.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-5144
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: LoongArch: csum: Fix OoB access in IP checksum code for negative lengths Commit 69e3a6aa6be2 ("LoongArch: Add checksum optimization for 64-bit system") would cause an undefined shift and an out-of-bounds read.…
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Commit 8bd795fedb84 ("arm64: csum: Fix OoB access in IP checksum code for negative lengths") fixes the same issue on ARM64.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation directly finds out-of-bounds read flaws through static analysis, fuzzing, and dynamic bounds checks.
Secure engineering principles require bounds checking and memory-safe constructs that stop out-of-bounds reads from being introduced.
Process isolation confines the effects of an out-of-bounds read to the compromised process.
Input validation rejects malformed indices or lengths that would otherwise cause reads outside buffer bounds.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices such as bounds checking and memory-safe languages directly prevent out-of-bounds reads.
Vulnerability scanning and recording can discover instances of out-of-bounds reads after code is deployed.
Routine patching replaces vulnerable code containing out-of-bounds read flaws.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development and acceptance includes fuzzing and static analysis that detect out-of-bounds read defects before release.
Secure coding standards explicitly forbid unsafe pointer arithmetic and mandate bounds-checked reads, eliminating CWE-125.