NVD / CVE Program· CNA Linux

CVE-2026-64543: tipc: fix use-after-free of the discoverer in tipc_disc_rcv()

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: 0.12% (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 1579342d71133da7f00daa02c75cebec7372097b, 380413cdfd29fb9fa486c82889132b680c4983c5, 4da2ac7749411971e1b222b992da5a172ce45f98.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1579342d71133da7f00daa02c75cebec7372097b, 380413cdfd29fb9fa486c82889132b680c4983c5, 4da2ac7749411971e1b222b992da5a172ce45f98 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: tipc: fix use-after-free of the discoverer in tipc_disc_rcv() bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still dereferences b->disc in RX softirq under rcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv). L2 bearers are safe thanks to the synchronize_net() in tipc_disable_l2_media(), but the UDP bearer defers that call to the cleanup_bearer() workqueue, so the discoverer is freed with no grace period: BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149) Read of size 8 at addr ffff88802348b728 by task poc_tipc/184 <IRQ> tipc_disc_rcv (net/tipc/discover.c:149) tipc_rcv (net/tipc/node.c:2126) tipc_udp_recv (net/tipc/udp_media.c:391) udp_rcv (net/ipv4/udp.c:2643) ip_local_deliver_finish (net/ipv4/ip_input.c:241) </IRQ> Freed by task 181: kfree (mm/slub.c:6565) bearer_disable (net/tipc/bearer.c:418) tipc_nl_bearer_disable (net/tipc/bearer.c:1001) The bearer is freed with kfree_rcu(); free the discoverer the same way. Add an rcu_head to struct tipc_discoverer and free it and its skb from an RCU callback. Because the RCU callback (tipc_disc_free_rcu) lives in module text, a call_rcu() that is still pending when the tipc module is unloaded would invoke a freed function. Add an rcu_barrier() to tipc_exit() after the bearer subsystem has been torn down, so all pending discoverer callbacks have run before the module text goes away. Reachable from an unprivileged user namespace: the TIPCv2 genl family is netnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC and CONFIG_TIPC_MEDIA_UDP.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

Published: Jul 27, 2026
Updated: Nov 3, 2026
EPSS: 0.1% · 2th 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%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · Linux: 7.8; NVD has not scored this yet; the score shown is the CNA’s.

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.

—

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
- 4.17affected
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before 380413cdfd29fb9fa486c82889132b680c4983c5affected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before f05b3f4c78370469286879c765f5a1dd39dbcd32affected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before 4da2ac7749411971e1b222b992da5a172ce45f98affected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before 5e215bf1c47fdddf8203a0fe80a0ed594065f101affected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before ec7d54d8cc1723921d671e3272b427c96366506faffected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2affected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before b65289e1c3f352a9f92c6e19713ddd647e033253affected · git
- 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 and later · before 1579342d71133da7f00daa02c75cebec7372097baffected · git
- before 4.17not 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 6.1.187-1	6.1.187-1
Debian:12	linux-6.12	before 6.12.100-1~deb12u1	6.12.100-1~deb12u1
Debian:13	linux	before 6.12.100-1	6.12.100-1
Debian:14	linux	before 7.1.5-1	7.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
40Plan
CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
40Plan
CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
40Plan

Published before and after this one in the same product

← EarlierCVE-2026-64541Jul 27, 2026 · net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket
39Monitor
← EarlierCVE-2026-64542Jul 27, 2026 · ipv6: ndisc: fix NULL deref in accept_untracked_na()
0Monitor
Later →CVE-2026-64544Jul 27, 2026 · crypto: asymmetric_keys - fix OOB read in pefile_digest_pe_contents
0Monitor

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	1579342d71133da7f00daa02c75cebec7372097b	Vendor (CNA)
Linux Linux	380413cdfd29fb9fa486c82889132b680c4983c5	Vendor (CNA)
Linux Linux	4da2ac7749411971e1b222b992da5a172ce45f98	Vendor (CNA)
Linux Linux	5e215bf1c47fdddf8203a0fe80a0ed594065f101	Vendor (CNA)
Linux Linux	a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2	Vendor (CNA)
Linux Linux	b65289e1c3f352a9f92c6e19713ddd647e033253	Vendor (CNA)
Linux Linux	ec7d54d8cc1723921d671e3272b427c96366506f	Vendor (CNA)
Linux Linux	f05b3f4c78370469286879c765f5a1dd39dbcd32	Vendor (CNA)
debian:linux	6.1.187-1 · Debian:12	Package registry (OSV)
debian:linux-6.12	6.12.100-1~deb12u1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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.

CVE-2026-645410 days apartnet/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket
39Monitor
CVE-2026-645301 days apartnet/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle
39Monitor
CVE-2026-645232 days apartnet/handshake: Take a long-lived file reference at submit
39Monitor
CVE-2026-639798 days apartnet/handshake: hand off the pinned file reference to accept_doit
39Monitor
CVE-2026-645648 days apartsctp: don't free the ASCONF's own transport in DEL-IP processing
39Monitor
CVE-2026-6814414 days apartphonet: pep: fix use-after-free in pep_get_sb()
39Monitor

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-26-0649 · Jul 28, 2026(Linux Kernel Güvenlik Bildirimi)

All national notices →

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-secondary

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

SSVC exploitation— → noneOct 16, 2026, 5:07 PM UTC
Fix✗ → ✓Sep 28, 2026, 10:11 PM UTC

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

References

git.kernel.org/stable/c/1579342d71133da7f00daa02c75cebec7372097b

Show all references (7 more)

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

All records