CVE-2026-68136: linux NULL Pointer Dereference
Vulnerability summary
CVE-2026-68136 is a critical (CVSS 9.8) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.54% chance of exploitation in the next 30 days, higher than 44.2% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 27 · Related 25Timeline
- 10-08-2026PublishedVulnerability first disclosed.
- 19-10-2026Last modifiedVulnerability information updated.
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().
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.54%
Chance of exploitation in the next 30 days
Percentile
44%
Versus all other CVEs
30-day change
-0.01 pp
From 0.55% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu157 products
- linuxAll versions (No fix recorded) | < 6.8.0-147.147 | < 7.0.0-38.38
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 6.8.0-1067.70 | < 7.0.0-1014.14
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.1.187-1 | < 6.12.101-1 | < 7.1.6-1
- linux-6.12< 6.12.101-1~deb12u1
Linux1 product
- linux≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < 7fc7e35212cf58c134310fb47566a844297ceae9 | ≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < d1fb23f8f794ac4683127bd49a6422bd87e0ac02 | ≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < db3e82da616f52e2b27e25e7be3fde2f2a5e54d6 | ≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < 107e1a469f53a2a70874f3f12bf6fcd23925da1d | ≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < a4dfd46cc8f08a29c6183794790547d0945f3d45 | ≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < fc0c0f7a207f0cd2d2aa725696c907f7d03af9e0 | ≥ 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596, < e751256486d0ded20f5a9f9863467f1dce65142f | 5.6
3 vendors · 160 products
