# CVE-2026-80863: RDMA/rxe: Fix OOB in free_rd_atomic_resources()

> A local attacker with low privileges can trigger a slab out-of-bounds write in the Linux kernel RDMA subsystem, potentially leading to code execution or privilege escalation.

- **Severity:** Not scored
- **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:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99618, BELL-CVE-2026-80863, DEBIAN-CVE-2026-80863, GHSA-h28p-6hx4-vcc6, UBUNTU-CVE-2026-80863

## What is CVE-2026-80863?

CVE-2026-80863 is a memory corruption vulnerability in Linux, published on 4 Sep 2026. 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:

RDMA/rxe: Fix OOB in free_rd_atomic_resources()

free_rd_atomic_resources() iterates using qp->attr.max_dest_rd_atomic.
Updating max_dest_rd_atomic before freeing the old array can make the
free path walk past the old allocation and trigger a slab out-of-bounds
write catched by KASAN:
==================================================================
BUG: KASAN: slab-out-of-bounds in free_rd_atomic_resource drivers/infiniband/sw/rxe/rxe_qp.c:180 [inline]
BUG: KASAN: slab-out-of-bounds in free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:171 [inline]
BUG: KASAN: slab-out-of-bounds in free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:163 [inline]
BUG: KASAN: slab-out-of-bounds in rxe_qp_from_attr+0x1e88/0x2150 drivers/infiniband/sw/rxe/rxe_qp.c:712
Write of size 4 at addr ffff88802b8dddb8 by task syz.3.451/11063

CPU: 0 UID: 0 PID: 11063 Comm: syz.3.451 Not tainted 7.1.0 #2 PREEMPT(full)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x10e/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xf7/0x600 mm/kasan/report.c:482
 kasan_report+0xe4/0x120 mm/kasan/report.c:595
 free_rd_atomic_resource drivers/infiniband/sw/rxe/rxe_qp.c:180 [inline]
 free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:171 [inline]
 free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:163 [inline]
 rxe_qp_from_attr+0x1e88/0x2150 drivers/infiniband/sw/rxe/rxe_qp.c:712
 rxe_modify_qp+0x1e2/0x530 drivers/infiniband/sw/rxe/rxe_verbs.c:623
 ib_security_modify_qp+0x223/0xfa0 drivers/infiniband/core/security.c:625
 _ib_modify_qp+0x333/0xec0 drivers/infiniband/core/verbs.c:1915
 modify_qp+0x13ca/0x1940 drivers/infiniband/core/uverbs_cmd.c:1932
 ib_uverbs_modify_qp+0xcb/0x120 drivers/infiniband/core/uverbs_cmd.c:1958
 ib_uverbs_write+0xb86/0x1030 drivers/infiniband/core/uverbs_main.c:680
 vfs_write+0x2aa/0x1070 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fefc75a70cd
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fefc8495018 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fefc7835fa0 RCX: 00007fefc75a70cd
RDX: 0000000000000078 RSI: 0000200000000240 RDI: 0000000000000007
RBP: 00007fefc764f10f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fefc7836038 R14: 00007fefc7835fa0 R15: 00007ffcf0586aa0
 </TASK>

Allocated by task 11063:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5296 [inline]
 __kmalloc_noprof+0x32a/0x850 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 alloc_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:155 [inline]
 rxe_qp_from_attr+0x3f8/0x2150 drivers/infiniband/sw/rxe/rxe_qp.c:714
 rxe_modify_qp+0x1e2/0x530 drivers/infiniband/sw/rxe/rxe_verbs.c:623
 ib_security_modify_qp+0x223/0xfa0 drivers/infiniband/core/security.c:625
 _ib_modify_qp+0x333/0xec0 drivers/infiniband/core/verbs.c:1915
 modify_qp+0x13ca/0x1940 drivers/infiniband/core/uverbs_cmd.c:1932
 ib_uverbs_modify_qp+0xcb/0x120 drivers/infiniband/core/uverbs_cmd.c:1958
 ib_uverbs_write+0xb86/0x1030 drivers/infiniband/core/uverbs_ma
---truncated---

## Which versions are affected by CVE-2026-80863?


## How do I fix CVE-2026-80863?

Apply the vendor's patch.

## Is CVE-2026-80863 being exploited?

There is no known exploitation of CVE-2026-80863 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80863 and fix it if it is affected.

What it is: CVE-2026-80863 is a memory corruption vulnerability in Linux, published on 4 Sep 2026. 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-2026-80863 in the wild and no public exploit code.

Affected product: Linux. 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-2026-80863/ (Markdown: https://insights.sbomify.com/CVE-2026-80863/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80863
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80863
- OSV: https://osv.dev/vulnerability/CVE-2026-80863

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80863/
Summaries are generated and may contain mistakes; the official description above is the record.