CVE-2026-74220
HIGH 8.8U-Boot before 2026.10-rc5 contains a buffer overflow in nfs_read_reply() function in net/nfs-common.c that allows attackers to corrupt memory by supplying crafted NFS READ reply lengths. A malicious NFS server can exploit signed integer handling to bypass length validation and write far past the destination buffer, crashing the bootloader or corrupting memory.
Severe if exploited (CVSS 8.8), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.3%chance of exploitation in 30 days · 27th percentile
Impact if exploited
8.8CVSS 4.0 · HIGH
- ConfidentialityNone
- IntegrityLow
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Data snapshot:
Weakness (CWE)
- CWE-195: Signed to Unsigned Conversion Error
CVSS 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
References and research data (JSON)
All CVSS metrics
- HIGH 8.8 v4.0 · CNA Primary
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 - HIGH 8.2 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - HIGH 8.8 v4.0 · NVD Secondary
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:X - HIGH 8.2 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
References
Patches & mitigations
- https://github.com/u-boot/u-boot/commit/0bbf09859658b8cc9ac13be41af23b516b8ef69a CVE record · VulnCheck · Updated 2026-09-29T21:29:22.617Z
NVD · CVE-2026-74220 · Updated 2026-09-30T16:40:50.560
Advisories
- https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc5-buffer-overflow-via-nfs-read-reply CVE record · VulnCheck · Updated 2026-09-29T21:29:22.617Z
NVD · CVE-2026-74220 · Updated 2026-09-30T16:40:50.560 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-89433 EUVD · EUVD-2026-89433
Technical & other
- https://github.com/u-boot/u-boot/blob/v2026.07/net/nfs-common.c#L695 CVE record · VulnCheck · Updated 2026-09-29T21:29:22.617Z
NVD · CVE-2026-74220 · Updated 2026-09-30T16:40:50.560 - https://github.com/u-boot/u-boot CVE record · VulnCheck · Updated 2026-09-29T21:29:22.617Z
NVD · CVE-2026-74220 · Updated 2026-09-30T16:40:50.560