CVE-2026-68118: tcp: challenge ACK for non-exact RST in SYN-RECEIVED

mediumCVSS 5.3CVE-2026-68118

CSIRTS triage

vendor: Linux product: Linux kernel Denial of service

What: The TCP stack incorrectly handles non-exact RST frames during SYN-RECEIVED state, allowing connection manipulation.
Who is affected: All systems running the Linux kernel with TCP networking enabled.
Urgency: Moderate; CVSS 5.3 indicates medium severity; exploitability depends on network topology and attacker position.
Action: Apply kernel patch or implement network-level filtering for malformed RST packets.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch Linux kernel

Get an email when a new Linux kernel advisory drops — max one per day, one-click unsubscribe.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.3
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68118

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-681180.38% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 32% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-68118	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for tcp

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

criticalCVE-2026-74569: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_si…nvd · 2026-08-15
highCVE-2026-74563: In the Linux kernel, the following vulnerability has been resolved: rds: tcp: hold the RCU loc…nvd · 2026-08-15
criticalCVE-2026-74556: In the Linux kernel, the following vulnerability has been resolved: scsi: libiscsi_tcp: Bound …nvd · 2026-08-15
unknownCVE-2026-74386: In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: fix page fragme…nvd · 2026-08-15
highCVE-2026-74385: In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: check return va…nvd · 2026-08-15
criticalCVE-2026-74268: In the Linux kernel, the following vulnerability has been resolved: tcp: clear sock_ops cb fla…nvd · 2026-08-15