CVE-2026-74656: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-4hv8-gc9j-4wjf
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CVSS 7.8
Published
Advisory Summary

CVE-2026-74656 is a HIGH (CVSS 7.8) security vulnerability vulnerability (General Security Weakness) affecting Software libraries in the Maven ecosystem. Remediation is available in the latest vendor maintenance releases.

CVE-2026-74656 at a Glance

CVE Identifier CVE-2026-74656
GHSA Identifier GHSA-4hv8-gc9j-4wjf
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification General Security Weakness
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-74656

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-74656, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under General Security Weakness. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

In the Linux kernel, the following vulnerability has been resolved: ipv4: fix use-after-free in fib_nhc_update_mtu() fib_nhc_update_mtu() walks the nexthop exception table under RTNL, but RTNL does not serialize this walk with PMTU exception updates. The walk uses rcu_dereference_protected() with a constant true condition without holding fnhe_lock. The following interleaving can therefore occur: CPU 0 CPU 1 fib_nhc_update_mtu() update_or_create_fnhe() load fnhe spin_lock_bh(&fnhe_lock) fnhe_remove_oldest() unlink fnhe kfree_rcu(fnhe, rcu) <quiescent state> access fnhe after grace period KASAN reported: BUG: KASAN: slab-use-after-free in fib_nhc_update_mtu+0x3df/0x410 Read of size 8 at addr ffff888107d49000 by task poc/90 Call Trace: fib_nhc_update_mtu+0x3df/0x410 fib_sync_mtu+0x7a/0xd0 fib_netdev_event+0x229/0x3f0 netif_set_mtu_ext+0x33a/0x570 dev_set_mtu+0x88/0x120 The same walk updates fnhe_pmtu and fnhe_mtu_locked. These fields form a pair and other writers serialize them with fnhe_lock. RCU alone prevents reclamation, but would still allow concurrent writers to leave a mixed pair. Walk the table under RCU and acquire fnhe_lock only while updating each exception. RCU keeps the current entry alive while the short critical section serializes its paired PMTU fields. This avoids holding the global lock while scanning all 2048 buckets for every nexthop.

References

NVD — CVE-2026-74656 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-74656
git.kernel.org/stable/c/5a28a4b22d... WEB
https://git.kernel.org/stable/c/5a28a4b22dde92f9d293b94236314b8d6181dc4a
git.kernel.org/stable/c/63996ffc59... WEB
https://git.kernel.org/stable/c/63996ffc594d128ccec8fc0983f91effd2d3adc4
git.kernel.org/stable/c/bc5bde9ce3... WEB
https://git.kernel.org/stable/c/bc5bde9ce3cc36502839dfe98e068f7303a50982
git.kernel.org/stable/c/dfe388da13... WEB
https://git.kernel.org/stable/c/dfe388da13aa784851e5ebbea90afbb099075761
git.kernel.org/stable/c/e00f7d2b5f... WEB
https://git.kernel.org/stable/c/e00f7d2b5f2540a3415a229c982af7a25ff6362e
git.kernel.org/stable/c/e1e602d6b2... WEB
https://git.kernel.org/stable/c/e1e602d6b22d5cb1641c4459c487eb18bf569e0a
git.kernel.org/stable/c/ed503eaad6... WEB
https://git.kernel.org/stable/c/ed503eaad62f20cdd5122d7c3078a648a99c8f16
git.kernel.org/stable/c/fd39e71186... WEB
https://git.kernel.org/stable/c/fd39e711866498ae94fcf9acf6f422a4f045b681

Frequently Asked Questions

What is CVE-2026-74656?
CVE-2026-74656 is a security vulnerability in Software classified as a security vulnerability vulnerability under General Security Weakness.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-74656?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-74656?
CVE-2026-74656 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-74656?
CVE-2026-74656 is classified under General Security Weakness.
How can I check Maven dependencies for CVE-2026-74656?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4hv8-gc9j-4wjf",
  "modified" : "2026-08-25T06:31:25Z",
  "published" : "2026-08-22T18:30:28Z",
  "aliases" : [ "CVE-2026-74656" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fix use-after-free in fib_nhc_update_mtu()\n\nfib_nhc_update_mtu() walks the nexthop exception table under RTNL, but\nRTNL does not serialize this walk with PMTU exception updates. The walk\nuses rcu_dereference_protected() with a constant true condition without\nholding fnhe_lock.\n\nThe following interleaving can therefore occur:\n\n  CPU 0                              CPU 1\n  fib_nhc_update_mtu()               update_or_create_fnhe()\n    load fnhe                          spin_lock_bh(&fnhe_lock)\n                                       fnhe_remove_oldest()\n                                         unlink fnhe\n                                         kfree_rcu(fnhe, rcu)\n    <quiescent state>\n    access fnhe after grace period\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in fib_nhc_update_mtu+0x3df/0x410\n  Read of size 8 at addr ffff888107d49000 by task poc/90\n  Call Trace:\n   fib_nhc_update_mtu+0x3df/0x410\n   fib_sync_mtu+0x7a/0xd0\n   fib_netdev_event+0x229/0x3f0\n   netif_set_mtu_ext+0x33a/0x570\n   dev_set_mtu+0x88/0x120\n\nThe same walk updates fnhe_pmtu and fnhe_mtu_locked. These fields form a\npair and other writers serialize them with fnhe_lock. RCU alone prevents\nreclamation, but would still allow concurrent writers to leave a mixed\npair.\n\nWalk the table under RCU and acquire fnhe_lock only while updating each\nexception. RCU keeps the current entry alive while the short critical\nsection serializes its paired PMTU fields. This avoids holding the global\nlock while scanning all 2048 buckets for every nexthop.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-74656"
  }, {
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    "url" : "https://git.kernel.org/stable/c/5a28a4b22dde92f9d293b94236314b8d6181dc4a"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/63996ffc594d128ccec8fc0983f91effd2d3adc4"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/bc5bde9ce3cc36502839dfe98e068f7303a50982"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/dfe388da13aa784851e5ebbea90afbb099075761"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/e00f7d2b5f2540a3415a229c982af7a25ff6362e"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/e1e602d6b22d5cb1641c4459c487eb18bf569e0a"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/ed503eaad62f20cdd5122d7c3078a648a99c8f16"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/fd39e711866498ae94fcf9acf6f422a4f045b681"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-22T16:16:39Z"
  }
}