Linux Kernel up to 6.19-rc4 net skb_segment_list reference count

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Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 6.1.160/6.6.120/6.12.65/6.18.5/6.19-rc4. This issue affects the function skb_segment_list of the component net. The manipulation results in reference count. This vulnerability was named CVE-2026-22979. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.1.160/6.6.120/6.12.65/6.18.5/6.19-rc4. Affected is the function skb_segment_list of the component net. The manipulation with an unknown input leads to a reference count vulnerability. CWE is classifying the issue as CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net: fix memory leak in skb_segment_list for GRO packets When skb_segment_list() is called during packet forwarding, it handles packets that were aggregated by the GRO engine. Historically, the segmentation logic in skb_segment_list assumes that individual segments are split from a parent SKB and may need to carry their own socket memory accounting. Accordingly, the code transfers truesize from the parent to the newly created segments. Prior to commit ed4cccef64c1 ("gro: fix ownership transfer"), this truesize subtraction in skb_segment_list() was valid because fragments still carry a reference to the original socket. However, commit ed4cccef64c1 ("gro: fix ownership transfer") changed this behavior by ensuring that fraglist entries are explicitly orphaned (skb->sk = NULL) to prevent illegal orphaning later in the stack. This change meant that the entire socket memory charge remained with the head SKB, but the corresponding accounting logic in skb_segment_list() was never updated. As a result, the current code unconditionally adds each fragment's truesize to delta_truesize and subtracts it from the parent SKB. Since the fragments are no longer charged to the socket, this subtraction results in an effective under-count of memory when the head is freed. This causes sk_wmem_alloc to remain non-zero, preventing socket destruction and leading to a persistent memory leak. The leak can be observed via KMEMLEAK when tearing down the networking environment: unreferenced object 0xffff8881e6eb9100 (size 2048): comm "ping", pid 6720, jiffies 4295492526 backtrace: kmem_cache_alloc_noprof+0x5c6/0x800 sk_prot_alloc+0x5b/0x220 sk_alloc+0x35/0xa00 inet6_create.part.0+0x303/0x10d0 __sock_create+0x248/0x640 __sys_socket+0x11b/0x1d0 Since skb_segment_list() is exclusively used for SKB_GSO_FRAGLIST packets constructed by GRO, the truesize adjustment is removed. The call to skb_release_head_state() must be preserved. As documented in commit cf673ed0e057 ("net: fix fraglist segmentation reference count leak"), it is still required to correctly drop references to SKB extensions that may be overwritten during __copy_skb_header().

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-22979 since 01/13/2026. The exploitability is told to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 296404 (Linux Distros Unpatched Vulnerability : CVE-2026-22979), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.161, 6.6.121, 6.12.66, 6.18.6 or 6.19-rc5 eliminates this vulnerability. Applying the patch 0b27828ebd1ed3107d7929c3737adbe862e99e74/88bea149db2057112af3aaf63534b24fab5858ab/3264881431e308b9c72cb8a0159d57a56d67dd79/c114a32a2e70b82d447f409f7ffcfa3058f9d5bd/238e03d0466239410b72294b79494e43d4fabe77 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (296404) and CERT Bund (WID-SEC-2026-0215). Once again VulDB remains the best source for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • RESF Rocky Linux
  • NetApp ActiveIQ Unified Manager
  • Open Source Linux Kernel

Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 5.0

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Reference count
CWE: CWE-911 / CWE-664
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 296404
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-22979

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.161/6.6.121/6.12.66/6.18.6/6.19-rc5
Patch: 0b27828ebd1ed3107d7929c3737adbe862e99e74/88bea149db2057112af3aaf63534b24fab5858ab/3264881431e308b9c72cb8a0159d57a56d67dd79/c114a32a2e70b82d447f409f7ffcfa3058f9d5bd/238e03d0466239410b72294b79494e43d4fabe77

Timelineinfo

01/13/2026 CVE reserved
01/23/2026 +10 days Advisory disclosed
01/23/2026 +0 days VulDB entry created
05/17/2026 +114 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-22979 (🔒)
GCVE (CVE): GCVE-0-2026-22979
GCVE (VulDB): GCVE-100-342588
CERT Bund: WID-SEC-2026-0215 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 01/23/2026 17:26
Updated: 05/17/2026 20:05
Changes: 01/23/2026 17:26 (59), 01/25/2026 10:02 (2), 02/27/2026 02:04 (11), 03/02/2026 10:01 (7), 05/17/2026 20:05 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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