CVE-2026-68136
net: gro: fix double aggregation of flush-marked skbs
Description
In the Linux kernel, the following vulnerability has been resolved: net: gro: fix double aggregation of flush-marked skbs Commit 0ab03f353d36 ("net-gro: Fix GRO flush when receiving a GSO packet.") added a flush check to skb_gro_receive(), but skb_gro_receive_list() lacks the same validation. As a result, packets marked with NAPI_GRO_CB(skb)->flush may still be re-aggregated. This allows already-GRO'd packets with existing frag_list to be re-aggregated into a new GRO session, corrupting the frag_list chain structure. When skb_segment() attempts to unpack these malformed packets, it encounters invalid state and triggers a kernel panic. Scenario (Tethering/Device forwarding): 1. Driver: Generated aggregated packet P1 via LRO with frag_list 2. Dev A: Receives aggregated fraglist packet and flush flag set 3. Dev A: Re-enters GRO, skb_gro_receive_list() is called 4. Missing flush check allows re-aggregation despite flush flag 5. Frag_list chain becomes corrupted (loops or dangling refs) 6. Dev B: TX path calls skb_segment(), crashes on corrupted frag_list Root cause in skb_segment(): The check at line ~4891: if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) && (skb_headlen(list_skb) == len || sg)) { When frag_list is corrupted by double aggregation, when list_skb is a NULL pointer from skb->next, skb_headlen(list_skb) dereference NULL/corrupted pointers occurs. Call Trace: skb_headlen(NULL skb) skb_segment tcp_gso_segment tcp4_gso_segment inet_gso_segment skb_mac_gso_segment __skb_gso_segment skb_gso_segment validate_xmit_skb validate_xmit_skb_list sch_direct_xmit qdisc_restart __qdisc_run qdisc_run net_tx_action Fix: Add NAPI_GRO_CB(skb)->flush validation to the early-return check in skb_gro_receive_list(), matching the defensive programming pattern of skb_gro_receive().
INFO
Published Date :
Aug. 10, 2026, 1:19 p.m.
Last Modified :
Aug. 13, 2026, 11:17 p.m.
Remotely Exploit :
Yes !
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Apply the Linux kernel commit 0ab03f353d36.
- Validate flush flag in skb_gro_receive_list().
- Ensure frag_list integrity during aggregation.
- Update the Linux kernel to the patched version.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-68136.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-68136 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-68136
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2026-68136 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-68136 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 13, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 10, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3a1296a38d0cf62bffb9a03c585cbd5dbf15d596', 'lessThan': '107e1a469f53a2a70874f3f12bf6fcd23925da1d', 'versionType': 'git'}, {'status': 'affected', 'version': '3a1296a38d0cf62bffb9a03c585cbd5dbf15d596', 'lessThan': 'a4dfd46cc8f08a29c6183794790547d0945f3d45', 'versionType': 'git'}, {'status': 'affected', 'version': '3a1296a38d0cf62bffb9a03c585cbd5dbf15d596', 'lessThan': 'fc0c0f7a207f0cd2d2aa725696c907f7d03af9e0', 'versionType': 'git'}, {'status': 'affected', 'version': '3a1296a38d0cf62bffb9a03c585cbd5dbf15d596', 'lessThan': 'e751256486d0ded20f5a9f9863467f1dce65142f', 'versionType': 'git'}], 'programFiles': ['net/core/gro.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.12.101', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/core/gro.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: net: gro: fix double aggregation of flush-marked skbs Commit 0ab03f353d36 ("net-gro: Fix GRO flush when receiving a GSO packet.") added a flush check to skb_gro_receive(), but skb_gro_receive_list() lacks the same validation. As a result, packets marked with NAPI_GRO_CB(skb)->flush may still be re-aggregated. This allows already-GRO'd packets with existing frag_list to be re-aggregated into a new GRO session, corrupting the frag_list chain structure. When skb_segment() attempts to unpack these malformed packets, it encounters invalid state and triggers a kernel panic. Scenario (Tethering/Device forwarding): 1. Driver: Generated aggregated packet P1 via LRO with frag_list 2. Dev A: Receives aggregated fraglist packet and flush flag set 3. Dev A: Re-enters GRO, skb_gro_receive_list() is called 4. Missing flush check allows re-aggregation despite flush flag 5. Frag_list chain becomes corrupted (loops or dangling refs) 6. Dev B: TX path calls skb_segment(), crashes on corrupted frag_list Root cause in skb_segment(): The check at line ~4891: if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) && (skb_headlen(list_skb) == len || sg)) { When frag_list is corrupted by double aggregation, when list_skb is a NULL pointer from skb->next, skb_headlen(list_skb) dereference NULL/corrupted pointers occurs. Call Trace: skb_headlen(NULL skb) skb_segment tcp_gso_segment tcp4_gso_segment inet_gso_segment skb_mac_gso_segment __skb_gso_segment skb_gso_segment validate_xmit_skb validate_xmit_skb_list sch_direct_xmit qdisc_restart __qdisc_run qdisc_run net_tx_action Fix: Add NAPI_GRO_CB(skb)->flush validation to the early-return check in skb_gro_receive_list(), matching the defensive programming pattern of skb_gro_receive(). Added Reference https://git.kernel.org/stable/c/107e1a469f53a2a70874f3f12bf6fcd23925da1d Added Reference https://git.kernel.org/stable/c/a4dfd46cc8f08a29c6183794790547d0945f3d45 Added Reference https://git.kernel.org/stable/c/e751256486d0ded20f5a9f9863467f1dce65142f Added Reference https://git.kernel.org/stable/c/fc0c0f7a207f0cd2d2aa725696c907f7d03af9e0