CVE-2026-71973: U-Boot before 2026.10-rc4 contains an integer overflow vulnerability in sqfs_read_directory_table() function when allocating the directory table
Affects u-bootSource GCVE Database
Not known to be exploited · CVSS 5.2 Medium : upgrade to 2026.10-rc4 when convenient.
Data as of 12 Nov 2026, 23:24 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2026.10-rc4
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 29 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.
What to do
Upgrade u-boot/u-boot to 2026.10-rc4.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubu-boot/u-bootpkg:github/u-boot/u-bootOther threats | Affected
| Fixed in
|
Ubuntu Pro 16.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra-legacy/xenialOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSu-boot-nezhapkg:deb/ubuntu/u-boot-nezha?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until then, avoid processing untrusted SquashFS images with vulnerable U-Boot versions.
Description
U-Boot versions prior to 2026.10-rc4 contain an integer overflow vulnerability in the sqfs_read_directory_table() function. This flaw occurs when processing a crafted SquashFS image with a malicious superblock metablks_count value, leading to heap buffer under-allocation and out-of-bounds writes. The vulnerability can cause heap memory corruption and bootloader crashes. The CVSS 3.1 base score is 5.2, indicating medium severity. No known exploits are reported in the wild. Affected versions include many specific Ubuntu package versions and all versions before 2026.10-rc4.
References
- nvd.nist.gov/vuln/detail/CVE-2026-71973 (opens in a new tab)
- github.com/u-boot/u-boot/commit/561ae28cb56a082cfa90c1c421c4955bc215470b (opens in a new tab)
- github.com/u-boot/u-boot (opens in a new tab)
- github.com/u-boot/u-boot/blob/v2026.07/fs/squashfs/sqfs.c (opens in a new tab)
- vulncheck.com/advisories/u-boot-before-2026.10-rc4-integer-overflow-in-squashfs-directory-table-allocation (opens in a new tab)
- ubuntu.com/security/CVE-2026-71973 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-71973 (opens in a new tab)