NVD / CVE Program· CNA Linux

CVE-2023-53338: lwt: Fix return values of BPF xmit ops

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: 0.55% (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 065d5f17096ec9161180e2c890afdff4dc6125f2, 29b22badb7a84b783e3a4fffca16f7768fb31205, 65583f9e070db7bece20710cfa2e3daeb0b831d9.
Severity is disputed: the assigning authority (CNA) scores it 9.8, NVD 7.8.

Low priority for now. Upgrade to Linux Linux 065d5f17096ec9161180e2c890afdff4dc6125f2, 29b22badb7a84b783e3a4fffca16f7768fb31205, 65583f9e070db7bece20710cfa2e3daeb0b831d9 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: lwt: Fix return values of BPF xmit ops BPF encap ops can return different types of positive values, such like NET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function skb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return values would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in ip(6)_finish_output2. When this happens, skbs that have been freed would continue to the neighbor subsystem, causing use-after-free bug and kernel crashes. To fix the incorrect behavior, skb_do_redirect return values can be simply discarded, the same as tc-egress behavior. On the other hand, bpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU information. Thus convert its return values to avoid the conflict with LWTUNNEL_XMIT_CONTINUE.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2026-03326

Published: Sep 17, 2025
Updated: Aug 5, 2026
EPSS: 0.5% · 46th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.5%

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: 9.8; 2.0 point gap

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

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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 kernel4.10 and later · before 5.4.257
linux linux kernel5.5 and later · before 5.10.195
linux linux kernel5.11 and later · before 5.15.132
linux linux kernel5.16 and later · before 6.1.53
linux linux kernel6.2 and later · before 6.4.16
linux linux kernel6.5 and later · before 6.5.3

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
- 4.10affected
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before 67f8f2bae8e7ac72e09def2b667e44704c4d1ee1affected · git
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before a97f221651fcdc891166e9bc270e3d9bfa5a0080affected · git
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before e3f647e4b642f9f6d32795a16f92c116c138d2afaffected · git
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before 065d5f17096ec9161180e2c890afdff4dc6125f2affected · git
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before d68c17402442f5f494a2c3ebde5cb82f6aa9160aaffected · git
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before 65583f9e070db7bece20710cfa2e3daeb0b831d9affected · git
- 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 and later · before 29b22badb7a84b783e3a4fffca16f7768fb31205affected · git
- before 4.10not affected · semver
- 5.4.257 and later · up to and including 5.4.*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 6.1.55-1	6.1.55-1
Debian:13	linux	before 6.5.3-1	6.5.3-1

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-2023-53335Sep 17, 2025 · RDMA/cxgb4: Fix potential null-ptr-deref in pass_establish()
22Monitor
← EarlierCVE-2023-53337Sep 17, 2025 · nilfs2: do not write dirty data after degenerating to read-only
22Monitor
Later →CVE-2023-53339Sep 17, 2025 · btrfs: fix BUG_ON condition in btrfs_cancel_balance
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	065d5f17096ec9161180e2c890afdff4dc6125f2	Vendor (CNA)
Linux Linux	29b22badb7a84b783e3a4fffca16f7768fb31205	Vendor (CNA)
Linux Linux	65583f9e070db7bece20710cfa2e3daeb0b831d9	Vendor (CNA)
Linux Linux	67f8f2bae8e7ac72e09def2b667e44704c4d1ee1	Vendor (CNA)
Linux Linux	a97f221651fcdc891166e9bc270e3d9bfa5a0080	Vendor (CNA)
Linux Linux	d68c17402442f5f494a2c3ebde5cb82f6aa9160a	Vendor (CNA)
Linux Linux	e3f647e4b642f9f6d32795a16f92c116c138d2af	Vendor (CNA)
debian:linux	6.1.55-1 · 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, 10:11 PM UTC

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

References

git.kernel.org/stable/c/065d5f17096ec9161180e2c890afdff4dc6125f2

Show all references (6 more)

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

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