CVE-2026-74726
bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor
Description
In the Linux kernel, the following vulnerability has been resolved: bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing the promiscuity it set on the active slave. In that window the active slave can change under RTNL (RTM_DELLINK -> __bond_release_one() -> bond_alb_handle_active_change()), which already drops the promiscuity and clears primary_is_promisc. The monitor still acts on the stale decision: if the slave was removed with no failover, curr_active_slave is now NULL and the deref faults; if it failed over, the stale dev_set_promiscuity(-1) underflows the new slave's promiscuity counter and pins it in IFF_PROMISC. Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: b42 bond_alb_monitor RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Kernel panic - not syncing: Fatal exception Re-check primary_is_promisc (and curr_active_slave) after taking RTNL so the monitor only undoes an increment it still owns. The other bonding monitors already re-read state under RTNL in their commit phase (bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only one acting on the pre-trylock decision.
INFO
Published Date :
Aug. 22, 2026, 4:16 p.m.
Last Modified :
Aug. 22, 2026, 4:16 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Update the Linux kernel.
- Re-check primary_is_promisc under RTNL.
- Ensure monitor acts on current state.
- Prevent promiscuity counter underflow.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-74726.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-74726 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-74726
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2026-74726 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-74726 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 22, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': 'f7668762bf5fd6db9397de5c0514407489d9d815', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': '09add8d5cfa9c46828f51eaad162c36e86366b71', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': 'b82f51681a7a88c7d3c865e817a3340d42b5fa2a', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': 'dd148539fb4741d01c06b7d2c8bd84b01920756c', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': 'dccec0227ed8d9e36936d66e256b957dc2858468', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': '2faf75a8a06504071b4c0aea7e45a9cc49a4e187', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': '257c4a3a34d8f51efb00f35375a0c6ce3c8f6ce2', 'versionType': 'git'}, {'status': 'affected', 'version': 'd0e81b7e2246a41d068ecaf15aac9de570816d63', 'lessThan': '683c6ba6e58e6ed1037831ea97dd58d9c0e76b8d', 'versionType': 'git'}], 'programFiles': ['drivers/net/bonding/bond_alb.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.24'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.24', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.265', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.216', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.183', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.152', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.104', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.45', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.9', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['drivers/net/bonding/bond_alb.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing the promiscuity it set on the active slave. In that window the active slave can change under RTNL (RTM_DELLINK -> __bond_release_one() -> bond_alb_handle_active_change()), which already drops the promiscuity and clears primary_is_promisc. The monitor still acts on the stale decision: if the slave was removed with no failover, curr_active_slave is now NULL and the deref faults; if it failed over, the stale dev_set_promiscuity(-1) underflows the new slave's promiscuity counter and pins it in IFF_PROMISC. Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: b42 bond_alb_monitor RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Kernel panic - not syncing: Fatal exception Re-check primary_is_promisc (and curr_active_slave) after taking RTNL so the monitor only undoes an increment it still owns. The other bonding monitors already re-read state under RTNL in their commit phase (bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only one acting on the pre-trylock decision. Added Reference https://git.kernel.org/stable/c/09add8d5cfa9c46828f51eaad162c36e86366b71 Added Reference https://git.kernel.org/stable/c/257c4a3a34d8f51efb00f35375a0c6ce3c8f6ce2 Added Reference https://git.kernel.org/stable/c/2faf75a8a06504071b4c0aea7e45a9cc49a4e187 Added Reference https://git.kernel.org/stable/c/683c6ba6e58e6ed1037831ea97dd58d9c0e76b8d Added Reference https://git.kernel.org/stable/c/b82f51681a7a88c7d3c865e817a3340d42b5fa2a Added Reference https://git.kernel.org/stable/c/dccec0227ed8d9e36936d66e256b957dc2858468 Added Reference https://git.kernel.org/stable/c/dd148539fb4741d01c06b7d2c8bd84b01920756c Added Reference https://git.kernel.org/stable/c/f7668762bf5fd6db9397de5c0514407489d9d815