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NVD / CVE Program· CNA Linux

CVE-2026-52993: tipc: fix double-free in tipc_buf_append()

CriticalCVSS 9.8 · v3.1—Proof of concept Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.40% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 0274f24485fc38032d4093e463dc3ff5c7a667c9, 1d5e589055880fae229e229e1929e087dbe08cf3, 29940fff14110ca48c5ccc168d121665b51bb778; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.143.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0274f24485fc38032d4093e463dc3ff5c7a667c9, 1d5e589055880fae229e229e1929e087dbe08cf3, 29940fff14110ca48c5ccc168d121665b51bb778; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.143.1-1 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: tipc: fix double-free in tipc_buf_append() tipc_msg_validate() can potentially reallocate the skb it is validating, freeing the old one. In tipc_buf_append(), it was being called with a pointer to a local variable which was a copy of the caller's skb pointer. If the skb was reallocated and validation subsequently failed, the error handling path would free the original skb pointer, which had already been freed, leading to double-free. Fix this by checking if head now points to a newly allocated reassembled skb. If it does, reassign *headbuf for later freeing operations.

Published
Jun 24, 2026
Updated
Oct 19, 2026
EPSS
0.4% · 35th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
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.

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  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-52993

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  • when exploit code appears or is weaponized
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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.

VendorProduct
linuxlinux kernel

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

    • 4.15affected
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before a438975a6dcdbd70865978c021650d1485586f0baffected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before 4ee4deadaae7cb2e3d53af0fc889cf92a73413c0affected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before d3556656c6daebf8def751c7e71d11dd0a180d24affected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before 0274f24485fc38032d4093e463dc3ff5c7a667c9affected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before 4d104882bc815d4ec666ace9155f5f52715879a6affected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before 1d5e589055880fae229e229e1929e087dbe08cf3affected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before 29940fff14110ca48c5ccc168d121665b51bb778affected · git
    • d618d09a68e4eed7a435beb2e355250f6f40664a and later · before d293ca716e7d5dffdaecaf6b9b2f857a33dc3d3aaffected · git
    • before 4.15not affected · semver
Affected versions · NVD (7)

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

  • linux linux kernel4.15 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.141
  • linux linux kernel6.7 and later · before 6.12.91
  • linux linux kernel6.13 and later · before 6.18.33
  • linux linux kernel6.19 and later · before 7.0.10

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.40.1.el10_26.12.0-211.40.1.el10_2

+96

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-2026-52990Jun 24, 2026 · fsnotify: fix inode reference leak in fsnotify_recalc_mask()
    22Monitor
  • ← EarlierCVE-2026-52991Jun 24, 2026 · sched/psi: fix race between file release and pressure write
    31Monitor
  • Later →CVE-2026-52994Jun 24, 2026 · vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting
    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 / packageFixed versionSource
Linux Linux0274f24485fc38032d4093e463dc3ff5c7a667c9Vendor (CNA)
Linux Linux1d5e589055880fae229e229e1929e087dbe08cf3Vendor (CNA)
Linux Linux29940fff14110ca48c5ccc168d121665b51bb778Vendor (CNA)
Linux Linux4d104882bc815d4ec666ace9155f5f52715879a6Vendor (CNA)
Linux Linux4ee4deadaae7cb2e3d53af0fc889cf92a73413c0Vendor (CNA)
Linux Linuxa438975a6dcdbd70865978c021650d1485586f0bVendor (CNA)
Linux Linuxd293ca716e7d5dffdaecaf6b9b2f857a33dc3d3aVendor (CNA)
Linux Linuxd3556656c6daebf8def751c7e71d11dd0a180d24Vendor (CNA)
azl3 kernel 6.6.139.1-1 on Azure Linux 3.06.6.143.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:bpftool4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-devel4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-doc4.18.0-553.147.1.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
red hat:bpftool0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:bpftool-debuginfo0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-abi-stablelists0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-core0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-core0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-debuginfo0:4.18.0-553.147.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)

+17

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-09-30

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.

  1. Published
  2. First PoC+97 d
  3. TodayNov 12, 2026+141 d

Variant candidates

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

  • CVE-2026-6388825 days apartscsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
    39Monitor
  • CVE-2026-6438331 days apartsmb: client: fix double-free in SMB2_flush() replay
    39Monitor
  • CVE-2026-6438431 days apartsmb: client: fix change notify replay double-free
    39Monitor
  • CVE-2026-6438531 days apartsmb: client: fix double-free in SMB2_ioctl() replay
    39Monitor
  • CVE-2026-6438631 days apartsmb: client: fix query_info() replay double-free
    39Monitor
  • CVE-2026-6438731 days apartsmb: client: fix query directory replay double-free
    39Monitor

National notice (Türkiye Cybersecurity Directorate / USOM)

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

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • 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
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

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

nvd-secondary

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

  1. SSVC exploitation— → none
  2. Exploit maturitynone → poc
  3. Fix✗ → ✓

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

References

Show all references (14 more)

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

All records