# CVE-2024-26815: net/sched: taprio: proper TCA_TAPRIO_TC_ENTRY_INDEX check

> A local attacker can trigger a shift-out-of-bounds error in the Linux kernel's taprio scheduler by providing negative index values, causing a system crash.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Apr 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2024-26815, DEBIAN-CVE-2024-26815, GHSA-xr98-c22v-cfcg, UBUNTU-CVE-2024-26815

## What is CVE-2024-26815?

CVE-2024-26815 is a high-severity vulnerability in Linux kernel, published on 10 Apr 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net/sched: taprio: proper TCA_TAPRIO_TC_ENTRY_INDEX check

taprio_parse_tc_entry() is not correctly checking
TCA_TAPRIO_TC_ENTRY_INDEX attribute:

	int tc; // Signed value

	tc = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_INDEX]);
	if (tc >= TC_QOPT_MAX_QUEUE) {
		NL_SET_ERR_MSG_MOD(extack, "TC entry index out of range");
		return -ERANGE;
	}

syzbot reported that it could fed arbitary negative values:

UBSAN: shift-out-of-bounds in net/sched/sch_taprio.c:1722:18
shift exponent -2147418108 is negative
CPU: 0 PID: 5066 Comm: syz-executor367 Not tainted 6.8.0-rc7-syzkaller-00136-gc8a5c731fd12 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call Trace:
 <TASK>
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
  ubsan_epilogue lib/ubsan.c:217 [inline]
  __ubsan_handle_shift_out_of_bounds+0x3c7/0x420 lib/ubsan.c:386
  taprio_parse_tc_entry net/sched/sch_taprio.c:1722 [inline]
  taprio_parse_tc_entries net/sched/sch_taprio.c:1768 [inline]
  taprio_change+0xb87/0x57d0 net/sched/sch_taprio.c:1877
  taprio_init+0x9da/0xc80 net/sched/sch_taprio.c:2134
  qdisc_create+0x9d4/0x1190 net/sched/sch_api.c:1355
  tc_modify_qdisc+0xa26/0x1e40 net/sched/sch_api.c:1776
  rtnetlink_rcv_msg+0x885/0x1040 net/core/rtnetlink.c:6617
  netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543
  netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
  netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367
  netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908
  sock_sendmsg_nosec net/socket.c:730 [inline]
  __sock_sendmsg+0x221/0x270 net/socket.c:745
  ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584
  ___sys_sendmsg net/socket.c:2638 [inline]
  __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667
 do_syscall_64+0xf9/0x240
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f1b2dea3759
Code: 48 83 c4 28 c3 e8 d7 19 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd4de452f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1b2def0390 RCX: 00007f1b2dea3759
RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000555500000000 R09: 0000555500000000
R10: 0000555500000000 R11: 0000000000000246 R12: 00007ffd4de45340
R13: 00007ffd4de45310 R14: 0000000000000001 R15: 00007ffd4de45340

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2024-26815?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-26815?

Apply the vendor's patch.

## Is CVE-2024-26815 being exploited?

There is no known exploitation of CVE-2024-26815 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-26815 and fix it if it is affected.

What it is: CVE-2024-26815 is a high-severity vulnerability in Linux kernel, published on 10 Apr 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-26815 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-26815/ (Markdown: https://insights.sbomify.com/CVE-2024-26815/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26815
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26815
- OSV: https://osv.dev/vulnerability/CVE-2024-26815

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26815/
Summaries are generated and may contain mistakes; the official description above is the record.