Linux Kernel up to 7.1.4 nf_conntrack_irc parse_dcc off-by-one

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
9.5	$5k-$25k	0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.1.4. It has been classified as very critical. Affected is the function parse_dcc of the component nf_conntrack_irc. The manipulation leads to off-by-one. This vulnerability is uniquely identified as CVE-2026-80603. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.1.4 and classified as very critical. This issue affects the function parse_dcc of the component nf_conntrack_irc. The manipulation with an unknown input leads to a off-by-one vulnerability. Using CWE to declare the problem leads to CWE-193. A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read parse_dcc() treats data_end as an inclusive end pointer, but its only caller passes data_limit = ib_ptr + datalen, which points one past the last valid byte. The newline search loop iterates while tmp <= data_end, so when no newline is present, *tmp is read at tmp == data_end, one byte beyond the region filled by skb_header_pointer(). irc_buffer is kmalloc'd as MAX_SEARCH_SIZE + 1 bytes and datalen is capped at MAX_SEARCH_SIZE, so the stray read does not fault. The byte is uninitialized or stale; if it contains an ASCII digit, simple_strtoul will consume it and produce a wrong DCC IP or port in the conntrack expectation. The extra allocation byte is also a fragile guard: if the cap or allocation size changes, this becomes a real out-of-bounds read. Change the loop and its post-loop check to use strict less-than, consistent with the caller's exclusive-end convention. Update the function comment accordingly.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-80603 since 08/26/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/28/2026).

Upgrading to version 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40 or 7.1.5 eliminates this vulnerability. Applying the patch abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1/2b70f61f569bb29acb380e6f616a1bbdee15668f/2393f0bd7a467ad475598f3a5b9de27ca36e3037/aff589556ed772cb1c0c2d7b4d91ec45c0c39416/eeef3b81f449560653662df2dde6f6fe247c5365/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-3075). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.260
• 5.15.211
• 6.1.177
• 6.6.144
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
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• 6.12.55
• 6.12.56
• 6.12.57
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• 6.12.70
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• 6.12.72
• 6.12.73
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• 6.12.77
• 6.12.78
• 6.12.79
• 6.12.80
• 6.12.81
• 6.12.82
• 6.12.83
• 6.12.84
• 6.12.85
• 6.12.86
• 6.12.87
• 6.12.88
• 6.12.89
• 6.12.90
• 6.12.91
• 6.12.92
• 6.12.93
• 6.12.94
• 6.12.95
• 6.12.96
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
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• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Off-by-one
CWE: CWE-193 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.261/5.15.212/6.1.178/6.6.145/6.12.97/6.18.40/7.1.5
Patch: abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1/2b70f61f569bb29acb380e6f616a1bbdee15668f/2393f0bd7a467ad475598f3a5b9de27ca36e3037/aff589556ed772cb1c0c2d7b4d91ec45c0c39416/eeef3b81f449560653662df2dde6f6fe247c5365/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a

Timelineinfo

08/26/2026 CVE reserved
08/28/2026 +2 days Advisory disclosed
08/28/2026 +0 days VulDB entry created
08/28/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-80603 (🔒)
GCVE (CVE): GCVE-0-2026-80603
GCVE (VulDB): GCVE-100-396527
CERT Bund: WID-SEC-2026-3075 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 08/28/2026 09:55
Updated: 08/28/2026 21:12
Changes: 08/28/2026 09:55 (59), 08/28/2026 21:12 (7)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

Discussion

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