# CVE-2021-47199: linux: In the Linux kernel, the following vulnerability has been resolved:  net/mlx5e: CT, Fix multiple allocations and meml...

CVE-2021-47199 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47199, released April 10, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47199
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 10, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  net/mlx5e: CT, Fix multiple allocations and memleak of mod acts  CT clear action offload adds additional mod hdr actions to the flow's original mod actions in order to clear the registers which hold ct_state. When such flow also includes encap action, a neigh update event can cause the driver to unoffload the flow and then reoffload it.  Each time this happens, the ct clear handling adds that same set of mod hdr actions to reset ct_state until the max of mod hdr actions is reached.  Also the driver never releases the allocated mod hdr actions and causing a memleak.  Fix above two issues by moving CT clear mod acts allocation into the parsing actions phase and only use it when offloading the rule. The release of mod acts will be done in the normal flow_put().   backtrace:     [<000000007316e2f3>] krealloc+0x83/0xd0     [<00000000ef157de1>] mlx5e_mod_hdr_alloc+0x147/0x300 [mlx5_core]     [<00000000970ce4ae>] mlx5e_tc_match_to_reg_set_and_get_id+0xd7/0x240 [mlx5_core]     [<0000000067c5fa17>] mlx5e_tc_match_to_reg_set+0xa/0x20 [mlx5_core]     [<00000000d032eb98>] mlx5_tc_ct_entry_set_registers.isra.0+0x36/0xc0 [mlx5_core]     [<00000000fd23b869>] mlx5_tc_ct_flow_offload+0x272/0x1f10 [mlx5_core]     [<000000004fc24acc>] mlx5e_tc_offload_fdb_rules.part.0+0x150/0x620 [mlx5_core]     [<00000000dc741c17>] mlx5e_tc_encap_flows_add+0x489/0x690 [mlx5_core]     [<00000000e92e49d7>] mlx5e_rep_update_flows+0x6e4/0x9b0 [mlx5_core]     [<00000000f60f5602>] mlx5e_rep_neigh_update+0x39a/0x5d0 [mlx5_core]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.15.5-1 | [DEBIAN-CVE-2021-47199](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47199.md) | Apr 10, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.15.5-1 | [DEBIAN-CVE-2021-47199](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47199.md) | Apr 10, 2024 |
| Linux | linux Debian 14 | 5.15.5-1 | [DEBIAN-CVE-2021-47199](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47199.md) | Apr 10, 2024 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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