high CVSS 8.2 EPSS <0.1%

CVE-2025-21890·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: idpf: fix checksums set in idpf_rx_rsc() idpf_rx_rsc() uses skb_transport_offset(skb) while the transport header is not set yet. This triggers the following warning for CONFIG_DEBUG_NET=y builds. DEBUG_NET_WARN_ON_ONCE(!skb_transport_header_was_set(skb)) [ 69.261620] WARNING: CPU: 7 PID: 0 at ./include/linux/skbuff.h:3020 idpf_vport_splitq_napi_poll (include/linux/skbuff.h:3020) idpf [ 69.261629] Modules linked in: vfat fat dummy bridge intel_uncore_frequency_tpmi intel_uncore_frequency_common intel_vsec_tpmi idpf intel_vsec cdc_ncm cdc_eem cdc_ether usbnet mii xhci_pci xhci_hcd ehci_pci ehci_hcd libeth [ 69.261644] CPU: 7 UID: 0 PID: 0 Comm: swapper/7 Tainted: G S W 6.14.0-smp-DEV #1697 [ 69.261648] Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN [ 69.261650] RIP: 0010:idpf_vport_splitq_napi_poll (include/linux/skbuff.h:3020) idpf [ 69.261677] ? __warn (kernel/panic.c:242 kernel/panic.c:748) [ 69.261682] ? idpf_vport_splitq_napi_poll (include/linux/skbuff.h:3020) idpf [ 69.261687] ? report_bug (lib/bug.c:?) [ 69.261690] ? handle_bug (arch/x86/kernel/traps.c:285) [ 69.261694] ? exc_invalid_op (arch/x86/kernel/traps.c:309) [ 69.261697] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:621) [ 69.261700] ? __pfx_idpf_vport_splitq_napi_poll (drivers/net/ethernet/intel/idpf/idpf_txrx.c:4011) idpf [ 69.261704] ? idpf_vport_splitq_napi_poll (include/linux/skbuff.h:3020) idpf [ 69.261708] ? idpf_vport_splitq_napi_poll (drivers/net/ethernet/intel/idpf/idpf_txrx.c:3072) idpf [ 69.261712] __napi_poll (net/core/dev.c:7194) [ 69.261716] net_rx_action (net/core/dev.c:7265) [ 69.261718] ? __qdisc_run (net/sched/sch_generic.c:293) [ 69.261721] ? sched_clock (arch/x86/include/asm/preempt.h:84 arch/x86/kernel/tsc.c:288) [ 69.261726] handle_softirqs (kernel/softirq.c:561)

Severity
high
Software
Kernel
Fixed in
6.13.6
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 15% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2025-21890 scores 8.2 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 6.13

Until: 6.13.6

Fixed in: 6.13.6

How to fix this CVE

Update your Linux kernel to version 6.13.6 or later to resolve a transport header initialization issue in the idpf driver. This vulnerability affects kernel versions 6.13 through 6.13.5 and causes debug warnings when CONFIG_DEBUG_NET is enabled. Apply the kernel update immediately to prevent potential stability issues in network receive processing.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed kernel version: uname -r
  2. Verify if idpf driver is loaded: lsmod | grep idpf
  3. Check for CONFIG_DEBUG_NET enabled: grep CONFIG_DEBUG_NET /boot/config-$(uname -r)
  4. Search kernel logs for idpf_vport_splitq_napi_poll warnings: dmesg | grep 'idpf_vport_splitq_napi_poll' or journalctl -k | grep 'idpf_vport_splitq_napi_poll'
  5. Confirm kernel patched version: uname -r should show 6.13.6 or later

FAQ

What is CVE-2025-21890?

CVE-2025-21890 is a medium-severity vulnerability in the Linux kernel's idpf (Intel Data Plane Development Kit) driver where the transport header offset is accessed before the transport header is properly initialized, triggering debug warnings and potential stability issues in network packet processing.

Is CVE-2025-21890 being actively exploited?

No, CVE-2025-21890 is not listed in CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available. This is primarily a stability and debug-mode issue rather than a remote execution risk.

What versions of Kernel are affected by CVE-2025-21890?

Linux kernel versions 6.13 through 6.13.5 are affected. Kernel 6.13.6 and later contain the fix.

How do I check if my server is vulnerable to CVE-2025-21890?

Run 'uname -r' to check your kernel version. If it shows 6.13 through 6.13.5 and 'lsmod | grep idpf' shows the idpf driver is loaded, your system is vulnerable.

Does Defensia detect CVE-2025-21890?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2025-21890 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-63795CVSS 10In the Linux kernel, the following vulnerability has been resolved: 9p: avoid putting oldfid in p9_client_walk() error path When p9_client_walk() is called with clone set to false, fid aliases oldfid. If the walk subsequently fails after the request has been sent, the error path jumps to clunk_fid, which currently calls p9_fid_put(fid) unconditionally. This drops a reference to oldfid even though ownership of oldfid remains with the caller. If this is the last reference, oldfid can be clunked and destroyed while the caller still expects it to be valid. A later use or put of oldfid can then trigger a use-after-free or refcount underflow. Fix this by only putting fid in the clunk_fid error path when it does not alias oldfid, matching the existing guard in the error path below. This can be triggered when a multi-component walk is split into multiple p9_client_walk() calls and a later non-cloning walk fails. A reproducer and refcount warning logs are available on request.
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References

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