NVD / CVE Program· CNA Linux

CVE-2025-21855: ibmvnic: Don't reference skb after sending to VIOS

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.43% (FIRST EPSS).
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Linux Linux 093b0e5c90592773863f300b908b741622eef597, 25dddd01dcc8ef3acff964dbb32eeb0d89f098e9, 501ac6a7e21b82e05207c6b4449812d82820f306; azl3 kernel 6.6.78.1-3 on Azure Linux 3.0 6.6.82.1-1.

Low priority for now. Upgrade to Linux Linux 093b0e5c90592773863f300b908b741622eef597, 25dddd01dcc8ef3acff964dbb32eeb0d89f098e9, 501ac6a7e21b82e05207c6b4449812d82820f306; azl3 kernel 6.6.78.1-3 on Azure Linux 3.0 6.6.82.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: ibmvnic: Don't reference skb after sending to VIOS Previously, after successfully flushing the xmit buffer to VIOS, the tx_bytes stat was incremented by the length of the skb. It is invalid to access the skb memory after sending the buffer to the VIOS because, at any point after sending, the VIOS can trigger an interrupt to free this memory. A race between reading skb->len and freeing the skb is possible (especially during LPM) and will result in use-after-free: ================================================================== BUG: KASAN: slab-use-after-free in ibmvnic_xmit+0x75c/0x1808 [ibmvnic] Read of size 4 at addr c00000024eb48a70 by task hxecom/14495 <...> Call Trace: [c000000118f66cf0] [c0000000018cba6c] dump_stack_lvl+0x84/0xe8 (unreliable) [c000000118f66d20] [c0000000006f0080] print_report+0x1a8/0x7f0 [c000000118f66df0] [c0000000006f08f0] kasan_report+0x128/0x1f8 [c000000118f66f00] [c0000000006f2868] __asan_load4+0xac/0xe0 [c000000118f66f20] [c0080000046eac84] ibmvnic_xmit+0x75c/0x1808 [ibmvnic] [c000000118f67340] [c0000000014be168] dev_hard_start_xmit+0x150/0x358 <...> Freed by task 0: kasan_save_stack+0x34/0x68 kasan_save_track+0x2c/0x50 kasan_save_free_info+0x64/0x108 __kasan_mempool_poison_object+0x148/0x2d4 napi_skb_cache_put+0x5c/0x194 net_tx_action+0x154/0x5b8 handle_softirqs+0x20c/0x60c do_softirq_own_stack+0x6c/0x88 <...> The buggy address belongs to the object at c00000024eb48a00 which belongs to the cache skbuff_head_cache of size 224 ==================================================================

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2025-12079

Published: Mar 12, 2025
Updated: Aug 5, 2026
EPSS: 0.4% · 38th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.4%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 8.6; 0.8 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linux linux kernel4.5 and later · before 6.1.130
linux linux kernel6.2 and later · before 6.6.80
linux linux kernel6.7 and later · before 6.12.17
linux linux kernel6.13 and later · before 6.13.5
linux linux kernel6.14

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 4.5affected
- 032c5e82847a2214c3196a90f0aeba0ce252de58 and later · before 501ac6a7e21b82e05207c6b4449812d82820f306affected · git
- 032c5e82847a2214c3196a90f0aeba0ce252de58 and later · before 093b0e5c90592773863f300b908b741622eef597affected · git
- 032c5e82847a2214c3196a90f0aeba0ce252de58 and later · before 25dddd01dcc8ef3acff964dbb32eeb0d89f098e9affected · git
- 032c5e82847a2214c3196a90f0aeba0ce252de58 and later · before abaff2717470e4b5b7c0c3a90e128b211a23da09affected · git
- 032c5e82847a2214c3196a90f0aeba0ce252de58 and later · before bdf5d13aa05ec314d4385b31ac974d6c7e0997c9affected · git
- before 4.5not affected · semver
- 6.1.130 and later · up to and including 6.1.*not affected · semver
- 6.6.80 and later · up to and including 6.6.*not affected · semver
- 6.12.17 and later · up to and including 6.12.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.133-1	6.1.133-1
Debian:13	linux	before 6.12.17-1	6.12.17-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2025-21852Mar 12, 2025 · net: Add rx_skb of kfree_skb to raw_tp_null_args[].
22Monitor
← EarlierCVE-2025-21854Mar 12, 2025 · sockmap, vsock: For connectible sockets allow only connected
22Monitor
Later →CVE-2025-21856Mar 12, 2025 · s390/ism: add release function for struct device
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Linux Linux	093b0e5c90592773863f300b908b741622eef597	Vendor (CNA)
Linux Linux	25dddd01dcc8ef3acff964dbb32eeb0d89f098e9	Vendor (CNA)
Linux Linux	501ac6a7e21b82e05207c6b4449812d82820f306	Vendor (CNA)
Linux Linux	abaff2717470e4b5b7c0c3a90e128b211a23da09	Vendor (CNA)
Linux Linux	bdf5d13aa05ec314d4385b31ac974d6c7e0997c9	Vendor (CNA)
azl3 kernel 6.6.78.1-3 on Azure Linux 3.0	6.6.82.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
debian:linux	6.1.133-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:10 PM UTC

For records you follow, these changes also arrive as notifications. →

References

git.kernel.org/stable/c/093b0e5c90592773863f300b908b741622eef597

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records