# CVE-2026-74222: U-Boot use-after-free in lwIP wget HTTP callback

Source: https://junglewise.ai/threats/cve-2026-74222-u-boot-before-2026-10-rc5-contains-a-use-after-free-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-74222 · Severity: high · CVSS 8.2 · Published 2026-09-29

U-Boot is a bootloader that initializes hardware and loads the operating system on embedded devices and systems. A use-after-free vulnerability in its HTTP download feature can crash the bootloader when downloading fails, potentially preventing devices from booting and creating a denial-of-service condition. An attacker with network access could trigger this by serving a malicious HTTP response, rendering affected devices inoperable until repaired or recovered.

Technologies: [U-Boot](https://junglewise.ai/threats/technologies/u-boot-u-boot). Vendors: [U-Boot](https://junglewise.ai/threats/vendors/u-boot).

## Quick answers

**Is CVE-2026-74222 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-74222 being exploited in the wild.

**How severe is CVE-2026-74222?** High severity, with a CVSS score of 8.2, published 29 September 2026.

**Which products and versions are affected?** U-Boot before 2026.10-rc5.

**Is there a fix for CVE-2026-74222?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-74222 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2026-74222?** Check whether you run U-Boot at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The httpc_recv_cb() callback function in the lwIP wget implementation frees a TCP protocol control block (PCB) but returns ERR_BUF instead of ERR_ABRT when HTTP data storage fails. This incorrect return code causes the TCP input path to continue processing the released PCB, leading to a use-after-free crash in the bootloader. The vulnerability affects U-Boot versions before 2026.10-rc5 and requires network access to trigger via a failed HTTP transfer.

## Affected products

- U-Boot U-Boot before 2026.10-rc5

## Timeline

- 2026-09-29: disclosed

## References

- [https://github.com/u-boot/u-boot](https://github.com/u-boot/u-boot)
- [https://github.com/u-boot/u-boot/blob/v2026.07/net/lwip/wget.c](https://github.com/u-boot/u-boot/blob/v2026.07/net/lwip/wget.c)

## Related threats

- [U-Boot out-of-bounds write in read_slotted_partition()](https://junglewise.ai/threats/cve-2026-71974-u-boot-before-2026-10-rc3-contains-an-out-of-bounds-write)
- [U-Boot out-of-bounds write in video_display_rle8_bitmap](https://junglewise.ai/threats/cve-2026-71972-u-boot-through-2026-10-rc5-contains-an-out-of-bounds-write)