net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM
CVSS score
—
EPSS probability
%0.2
Risk score
—
Published
2 mo ago
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Vulnerability description
DayBreach CVE AI Research
CVE-2026-68296 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.
In the Linux kernel, the following vulnerability has been resolved: net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM Before commit 00d066a4d4ed ("netdev_features: convert NETIF_F_LLTX to dev->lltx"), NETIF_F_LLTX was set unconditionally in both __gre_tunnel_init() and ip6gre_tnl_init_features() alongside GRE_FEATURES: dev->features |= GRE_FEATURES | NETIF_F_LLTX; When that commit converted NETIF_F_LLTX to the dev->lltx flag, it placed 'dev->lltx = true' after the SEQ/CSUM early returns instead of before them. This causes GRE/GRETAP/ip6gre tunnels with SEQ or CSUM+encap to lose lockless TX, reintroducing _xmit_lock acquisition around their ndo_start_xmit. Since GRE xmit re-enters the stack via ip_tunnel_xmit(), holding _xmit_lock risks ABBA deadlock with the underlay device. CPU0 CPU1 ---- ---- lock(&qdisc_xmit_lock_key#6); lock(&qdisc_xmit_lock_key#3); lock(&qdisc_xmit_lock_key#6); lock(&qdisc_xmit_lock_key#3); Fix by moving dev->lltx = true before the early returns in both functions, restoring the original unconditional behavior.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-68296 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
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SCORING: CVSS from Multiple Sources
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| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| The sources have not yet published a verified CVSS metric. | ||||
Patch and Remediation Guide
Solution & Remediation Advisory
3 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.
7.1.6-1Debian sid: 7.1.6-1
7.1.6-1Debian forky: 7.1.6-1
6.12.101-1Debian trixie: 6.12.101-1
Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-68296 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-2026-68296 weaknesses.
Official Sources and Advisories
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