CVE-2026-74221
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-74221 is a high-severity Signed to Unsigned Conversion Error (CWE-195) vulnerability. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 26th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-89434
Vulnerability Data
U-Boot before 2026.10-rc5 contains a buffer overflow in nfs_readlink_reply() function in net/nfs-common.c when processing NFS server responses. A malicious NFS server can send crafted READLINK replies with negative or oversized symlink length values to corrupt memory and crash the bootloader.
- 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 can discover conversion errors through static analysis, fuzzing, or targeted unit tests.
Requiring documented development standards and tools can enforce coding rules that prohibit or safely wrap such casts.
Engineering principles can mandate safe integer handling and strong typing to avoid unsafe signed-to-unsigned casts.
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 SDLC practices (static analysis, code review, safe-integer standards) directly prevent signed-to-unsigned conversion errors.
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.
Secure development life cycle mandates practices that can catch signed-to-unsigned conversion errors during design and coding.
A.8.26 only requires that security requirements (including resilience against attacks such as buffer overflows or SQL injection) be identified and specified during development or acquisition; it does not itself enforce, implement, or prevent the signed-to-unsigned conversion error from arising or being exploitable.
A.8.27 mandates establishing and applying security engineering principles (e.g. least privilege, security by design, hardening) and design reviews during the SDLC; it does not stop a signed-to-unsigned conversion error from being exploitable if the flawed code is written and deployed.
Secure coding standards directly prohibit unsafe signed-to-unsigned casts and require defensive checks.
Security testing in development can detect conversion-related defects before release.