CVE-2026-63923 (CVSS 8.8)

Description

In the Linux kernel, the following vulnerability has been resolved: octeontx2-af: validate body pcifunc in rvu_mbox_handler_rep_event_notify rvu_mbox_handler_rep_event_notify() in drivers/net/ethernet/marvell/ octeontx2/af/rvu_rep.c queues a sender-controlled REP_EVENT_NOTIFY request body verbatim, and rvu_rep_up_notify() then forwards event->pcifunc (the nested body field, distinct from the AF-normalised header pcifunc) into rvu_get_pfvf(), rvu_get_pf() and the AF->PF mailbox device index without any bounds check. A VF attached to a PF that has been put into switchdev representor mode reaches this path: the VF mailbox handler otx2_pfvf_mbox_handler() forwards every message id including MBOX_MSG_REP_EVENT_NOTIFY to AF without an allowlist, and the AF dispatcher rewrites only msg->pcifunc, leaving struct rep_event::pcifunc attacker-controlled. The sibling rvu_mbox_handler_esw_cfg() refuses requests whose header pcifunc is not rvu->rep_pcifunc; this handler has no equivalent gate. An out-of-range body pcifunc selects an &rvu->pf[]/&rvu->hwvf[] element past the allocated array and, for RVU_EVENT_MAC_ADDR_CHANGE, turns into a six-byte attacker-chosen OOB ether_addr_copy() target inside the queued worker; KASAN reports a slab-out-of-bounds write in rvu_rep_wq_handler. Reject malformed requests at the handler entry by gating on is_pf_func_valid(), which is already the canonical PF/VF range check in this driver; expose it via rvu.h so callers in rvu_rep.c can use it instead of open-coding the same range arithmetic.

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0015

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/2156a29aecfffa2eb7c558255690084efbe9f3b0 https://git.kernel.org/stable/c/68be0260e2a02ff9b18a8678d5f8d1715fa20138

Frequently Asked Questions

What is CVE-2026-63923? +

In the Linux kernel, the following vulnerability has been resolved: octeontx2-af: validate body pcifunc in rvu_mbox_handler_rep_event_notify rvu_mbox_handler_rep_event_notify() in drivers/net/ethernet/marvell/ octeontx2/af/rvu_rep.c queues a sender-controlled REP_EVENT_NOTIFY request body verbatim, and rvu_rep_up_notify() then forwards event->pcifunc (the nested body field, distinct from the AF-normalised header pcifunc) into rvu_get_pfvf(), rvu_get_pf() and the AF->PF mailbox device index without any bounds check. A VF attached to a PF that has been put into switchdev representor mode reaches this path: the VF mailbox handler otx2_pfvf_mbox_handler() forwards every message id including MBOX_MSG_REP_EVENT_NOTIFY to AF without an allowlist, and the AF dispatcher rewrites only msg->pcifunc, leaving struct rep_event::pcifunc attacker-controlled. The sibling rvu_mbox_handler_esw_cfg() refuses requests whose header pcifunc is not rvu->rep_pcifunc; this handler has no equivalent gate. An out-of-range body pcifunc selects an &rvu->pf[]/&rvu->hwvf[] element past the allocated array and, for RVU_EVENT_MAC_ADDR_CHANGE, turns into a six-byte attacker-chosen OOB ether_addr_copy() target inside the queued worker; KASAN reports a slab-out-of-bounds write in rvu_rep_wq_handler. Reject malformed requests at the handler entry by gating on is_pf_func_valid(), which is already the canonical PF/VF range check in this driver; expose it via rvu.h so callers in rvu_rep.c can use it instead of open-coding the same range arithmetic. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-63923? +

CVE-2026-63923 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0015, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-63923? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-63923