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CVE Record

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

In the Linux kernel, the following vulnerability has been resolved: tcp: challenge ACK for non-exact RST in SYN-RECEIVED The SYN-RECEIVED request-socket path in tcp_check_req() accepts an in-window RST without requiring SEG.SEQ to exactly match RCV.NXT. A non-exact RST therefore removes the request instead of eliciting a challenge ACK. RFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in SYN-RECEIVED: an exact RST resets the connection, while a non-exact in-window RST must trigger a challenge ACK and be dropped. Apply that check before the ACK-field validation, following the RFC sequence-number, RST, then ACK processing order. Factor the per-netns challenge ACK quota out of tcp_send_challenge_ack() so request sockets can share it. Use the request socket's send_ack() callback and its own out-of-window ACK timestamp to send and rate-limit the response.

HighCVSS 8.2Not KEV-listedUpdated
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Potential ATT&CK relevance

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CVE-2026-68118 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.2 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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1CVSS vectors
3Timeline events
1ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H3.94.2Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.2High
CVSS 3.1 vector shape for CVE-2026-68118Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

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  1. CVE reservedCVE Program

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  2. CVE publishedCVE Program

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  3. CVE updatedCVE Program

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ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux282f23c6ee343126156dd41218b22ece96d747e3, 282f23c6ee343126156dd41218b22ece96d747e3, 282f23c6ee343126156dd41218b22ece96d747e3, 282f23c6ee343126156dd41218b22ece96d747e3, 282f23c6ee343126156dd41218b22ece96d747e3, 86791bbfe5ed7b275be040cfeff049a1624af1b7, 61f69dc4e40e41b0018f00fa4aeb23d3239556fb, 34fb350281ced2a72707a5c0064f69992d440edb, 3.0.58, 3.2.37, 3.4.25unaffected
LinuxLinux3.6, 0, 6.6.153, 6.12.105, 6.18.42, 7.1.6, 7.2affected
Weakness

CWE details

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Improper Input Validation

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