CVE-2025-39990: Linux kernel · bpf: Check the helper function is valid in get_helper_proto
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 26 Oct 2026, 14:05 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.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-136.136?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1060.63?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14@6.14.0-1018.18~24.04.1?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1062.69?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11@6.11.0-1018.18~24.04.1?arch=source&distro=nobleOther 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
A fix for this vulnerability is available and has been applied in the Linux kernel. Users should update to a patched kernel version that includes the fix for CVE-2025-39990. Since this is not a cloud service, system administrators must manually apply the update to their affected Linux kernel versions.
Description
A vulnerability in the Linux kernel related to the BPF (Berkeley Packet Filter) subsystem has been resolved. The issue involved the kernel verifier not properly checking if a helper function pointer was valid, potentially allowing a NULL pointer due to a disabled configuration option. This was addressed by adding a direct check in the get_helper_proto function and marking the tail_call helper function pointer as poisoned since it is unused by design.
References
- ubuntu.com/security/CVE-2025-39990 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-39990 (opens in a new tab)
- git.kernel.org/linus/e4414b01c1cd9887bbde92f946c1ba94e40d6d64 (opens in a new tab)
- git.kernel.org/stable/c/3d429cb1278e995e22995ef117fa96d223a67e93 (opens in a new tab)
- git.kernel.org/stable/c/6233715b4b714068d6c831d214a4e8792109875a (opens in a new tab)
- git.kernel.org/stable/c/e4414b01c1cd9887bbde92f946c1ba94e40d6d64 (opens in a new tab)