Linux Kernel up to 7.1.8 ipv4 fib_nlmsg_size/fib_nexthop_info buffer size

CVSS Meta Temp Score
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CTI Interest Score
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7.2$5k-$25k0.43

Summaryinfo

A vulnerability has been found in Linux Kernel up to 7.1.8 and classified as critical. Affected by this issue is the function fib_nlmsg_size/fib_nexthop_info of the component ipv4. The manipulation leads to buffer size. This vulnerability is traded as CVE-2026-74657. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.1.8 and classified as critical. This issue affects the function fib_nlmsg_size/fib_nexthop_info of the component ipv4. The manipulation with an unknown input leads to a buffer size vulnerability. Using CWE to declare the problem leads to CWE-131. The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops fib_nlmsg_size() still estimates nexthop space as if every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA. As a result, route notifications can allocate an skb that is too small. fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With panic_on_warn set, this becomes a kernel panic. Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is actually present.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-74657 since 08/15/2026. 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 08/22/2026).

Upgrading to version 5.15.216, 6.1.183, 6.6.152, 6.12.104, 6.18.45 or 7.1.9 eliminates this vulnerability. Applying the patch 0f0ca602941d0a81ae9514943ca06c55159c6385/5307a53599fa762c06e475ee4a375252074fd324/7f80ad373ce4a7af5367ff273cea0f16e91387f3/4a5dfbae5179f6574695012a980476254df2d295/a59edda6eda1252340354322d8ab318b2e9052fb/9b22f13524fa0de0d963bbd3002df6c28bae3395/4ff9548d84945d2cbf9e4c207288063a200ea397 is able to eliminate this problem.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Buffer size
CWE: CWE-131 / CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.216/6.1.183/6.6.152/6.12.104/6.18.45/7.1.9
Patch: 0f0ca602941d0a81ae9514943ca06c55159c6385/5307a53599fa762c06e475ee4a375252074fd324/7f80ad373ce4a7af5367ff273cea0f16e91387f3/4a5dfbae5179f6574695012a980476254df2d295/a59edda6eda1252340354322d8ab318b2e9052fb/9b22f13524fa0de0d963bbd3002df6c28bae3395/4ff9548d84945d2cbf9e4c207288063a200ea397

Timelineinfo

08/15/2026 CVE reserved
08/22/2026 +7 days Advisory disclosed
08/22/2026 +0 days VulDB entry created
08/22/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74657 (🔒)
GCVE (CVE): GCVE-0-2026-74657
GCVE (VulDB): GCVE-100-394439

Entryinfo

Created: 08/22/2026 18:41
Changes: 08/22/2026 18:41 (59)
Complete: 🔍
Cache ID: 216::103

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