NVD / CVE Program· CNA Linux

CVE-2026-23319: bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim

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: 0.13% (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 3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2, 4e8a0005d633a4adc98e3b65d5080f93b90d356b, 529e685e522b9d7fb379dbe6929dcdf520e34c8c; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1.

Low priority for now. Upgrade to Linux Linux 3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2, 4e8a0005d633a4adc98e3b65d5080f93b90d356b, 529e685e522b9d7fb379dbe6929dcdf520e34c8c; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1 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: bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim The root cause of this bug is that when 'bpf_link_put' reduces the refcount of 'shim_link->link.link' to zero, the resource is considered released but may still be referenced via 'tr->progs_hlist' in 'cgroup_shim_find'. The actual cleanup of 'tr->progs_hlist' in 'bpf_shim_tramp_link_release' is deferred. During this window, another process can cause a use-after-free via 'bpf_trampoline_link_cgroup_shim'. Based on Martin KaFai Lau's suggestions, I have created a simple patch. To fix this: Add an atomic non-zero check in 'bpf_trampoline_link_cgroup_shim'. Only increment the refcount if it is not already zero. Testing: I verified the fix by adding a delay in 'bpf_shim_tramp_link_release' to make the bug easier to trigger: static void bpf_shim_tramp_link_release(struct bpf_link *link) { /* ... */ if (!shim_link->trampoline) return; + msleep(100); WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline, NULL)); bpf_trampoline_put(shim_link->trampoline); } Before the patch, running a PoC easily reproduced the crash(almost 100%) with a call trace similar to KaiyanM's report. After the patch, the bug no longer occurs even after millions of iterations.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2026-12301

Published: Mar 25, 2026
Updated: Oct 15, 2026
EPSS: 0.1% · 3th 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 · 0.1%

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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 kernel6.0.1 and later · before 6.1.167
linux linux kernel6.2 and later · before 6.6.130
linux linux kernel6.7 and later · before 6.12.77
linux linux kernel6.13 and later · before 6.18.17
linux linux kernel6.19 and later · before 6.19.7
linux linux kernel6.0
linux linux kernel7.0

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
- 6.0affected
- before 6.0not affected · semver
- 6.1.167 and later · up to and including 6.1.*not affected · semver
- 6.6.130 and later · up to and including 6.6.*not affected · semver
- 6.12.77 and later · up to and including 6.12.*not affected · semver
- 6.18.17 and later · up to and including 6.18.*not affected · semver
- 6.19.7 and later · up to and including 6.19.*not affected · semver
- 7.0 and laternot affected · original_commit_for_fix
- 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e and later · before 529e685e522b9d7fb379dbe6929dcdf520e34c8caffected · git
- 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e and later · before 9b02c5c4147f8af8ed783c8deb5df927a55c3951affected · git

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 6.1.170-1	6.1.170-1
Debian:13	linux	before 6.12.85-1	6.12.85-1
Debian:14	linux	before 6.19.8-1	6.19.8-1

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-2026-23317Mar 25, 2026 · drm/vmwgfx: Return the correct value in vmw_translate_ptr functions
31Monitor
← EarlierCVE-2026-23318Mar 25, 2026 · ALSA: usb-audio: Use correct version for UAC3 header validation
28Monitor
Later →CVE-2026-23321Mar 25, 2026 · mptcp: pm: in-kernel: always mark signal+subflow endp as used
22Monitor

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	3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2	Vendor (CNA)
Linux Linux	4e8a0005d633a4adc98e3b65d5080f93b90d356b	Vendor (CNA)
Linux Linux	529e685e522b9d7fb379dbe6929dcdf520e34c8c	Vendor (CNA)
Linux Linux	56145d237385ca0e7ca9ff7b226aaf2eb8ef368b	Vendor (CNA)
Linux Linux	9b02c5c4147f8af8ed783c8deb5df927a55c3951	Vendor (CNA)
Linux Linux	cfcfa0ca0212162aa472551266038e8fd6768cff	Vendor (CNA)
azl3 kernel 6.6.126.1-1 on Azure Linux 3.0	6.6.130.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
debian:linux	6.1.170-1 · 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, 10:09 PM UTC

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

References

git.kernel.org/stable/c/3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2

Show all references (9 more)

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

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