CVE-2026-98590: Linux kernel · bpf: Fix bpf_sock context code generation
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.5 Medium.
Data as of 28 Oct 2026, 01:28 UTC
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 18 Oct 2026
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 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bpf_sock context code generation Currently, the ctx access code reads the rx_queue_mapping field with either a 4-byte or 2-byte load. The rest of the bits in the register are marked known zero by the verifier. However, the emitted ctx access code places in the register on certain the special value (-1) using BPF_MOV_IMM64, which gets sign-extended to turn on all the bits in the register. By shifting this value right, the program ends up with a value at runtime above what the verifier assumes is possible. Fix this by ensuring the read value is as wide as the assumed size. Use MOV32 instructions instead of MOV64 instructions to keep the upper bits zero as assumed by the verifier. Also properly report the size of the destination variable (the bpf_sock field, 4 bytes) instead of the source (the socket field, 2 bytes).
References
- ubuntu.com/security/CVE-2026-98590 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98590 (opens in a new tab)
- git.kernel.org/stable/c/4a41d064facc3330e176ecbbf5b0026ed18a5c69 (opens in a new tab)
- git.kernel.org/stable/c/70288599d1754e157df8326239316dbdf08ea33c (opens in a new tab)
- git.kernel.org/stable/c/ea4dc96c902ccfa49dd3e4f23c443dab4a74b018 (opens in a new tab)
- git.kernel.org/stable/c/84ebb991ae985149079ae9ab51b7e3ba25a9ff53 (opens in a new tab)
- git.kernel.org/stable/c/4a4852376e3a2727ea40e61143d6d7c22bb6dfad (opens in a new tab)
- git.kernel.org/stable/c/d95dd5a6c6cd08d5ae466d3aed27b3cf59155a6c (opens in a new tab)
- git.kernel.org/stable/c/b3f37afc7fd7c52bc2114310aff1eb24c7cd4d73 (opens in a new tab)
- git.kernel.org/stable/c/e3ddcf4aeb342d4de2e5761c7042270d454752de (opens in a new tab)