CVE-2025-21765: ipv6: use RCU protection in ip6_default_advmss()
Noroxi assessment
Priority: Monitor (action score 22/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.61% (FIRST EPSS).
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: Linux Linux 28de355b63ad42309ed5a03ee7c436c90512265b, 3c8ffcd248da34fc41e52a46e51505900115fc2a, 4176a68b0db8fc74ac14fcd00ba8231371051dc2.
- Severity is disputed: the assigning authority (CNA) scores it 8.1, NVD 5.5.
Low priority for now. Upgrade to Linux Linux 28de355b63ad42309ed5a03ee7c436c90512265b, 3c8ffcd248da34fc41e52a46e51505900115fc2a, 4176a68b0db8fc74ac14fcd00ba8231371051dc2 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
In the Linux kernel, the following vulnerability has been resolved: ipv6: use RCU protection in ip6_default_advmss() ip6_default_advmss() needs rcu protection to make sure the net structure it reads does not disappear.
- Published
- Feb 27, 2025
- Updated
- Oct 15, 2026
- EPSS
- 0.6% · 49th percentile
- CWE
- —
Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
CNA vs NVD score
- NVD
- 5.5
- CNA · Linux
- 8.1
- 2.6 point gap
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Running WordPress? Scan your site free with WP Lens
Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| linux | linux kernel | cpe:2.3:o:linux:linux_kernel |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- linux linux kernel2.6.26 and later · before 5.4.291
- linux linux kernel5.5 and later · before 5.10.235
- linux linux kernel5.11 and later · before 5.15.179
- linux linux kernel5.16 and later · before 6.1.129
- linux linux kernel6.2 and later · before 6.6.79
- linux linux kernel6.7 and later · before 6.12.16
- linux linux kernel6.13 and later · before 6.13.4
- linux linux kernel6.14
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 2.6.26affected
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 78ad057472d8c76e0602402269222f9f9c698790affected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before d02f30d220ef9511568a48dba8a9004c65f8d904affected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 28de355b63ad42309ed5a03ee7c436c90512265baffected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 84212387caadb211cd9dadd6fd5563bd37dc1f5eaffected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 4176a68b0db8fc74ac14fcd00ba8231371051dc2affected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 713a40c892f40300d63691d9f85b2a23b48fe1e8affected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 550ed693f47370502a71b85382e7f9e6417300b8affected · git
- 5578689a4e3c04f2d43ea39736fd3fa396d80c6e and later · before 3c8ffcd248da34fc41e52a46e51505900115fc2aaffected · git
- before 2.6.26not affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | linux | before 6.1.129-1 | 6.1.129-1 |
| Debian:13 | linux | before 6.12.16-1 | 6.12.16-1 |
| SUSE:Linux Enterprise Micro 5.2 | kernel-default | before 5.3.18-150300.59.235.1 | 5.3.18-150300.59.235.1 |
| SUSE:Linux Enterprise Micro 5.2 | kernel-default-base | before 5.3.18-150300.59.235.1.150300.18.140.1 | 5.3.18-150300.59.235.1.150300.18.140.1 |
| SUSE:Linux Enterprise Micro 5.2 | kernel-rt | before 5.3.18-150300.235.1 | 5.3.18-150300.235.1 |
| SUSE:Linux Enterprise Micro 5.2 | kernel-source-rt | before 5.3.18-150300.235.1 | 5.3.18-150300.235.1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2025-21763Feb 27, 2025 · neighbour: use RCU protection in __neigh_notify()31Monitor
- ← EarlierCVE-2025-21764Feb 27, 2025 · ndisc: use RCU protection in ndisc_alloc_skb()31Monitor
- Later →CVE-2025-21766Feb 27, 2025 · ipv4: use RCU protection in __ip_rt_update_pmtu()22Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 28de355b63ad42309ed5a03ee7c436c90512265b | Vendor (CNA) |
| Linux Linux | 3c8ffcd248da34fc41e52a46e51505900115fc2a | Vendor (CNA) |
| Linux Linux | 4176a68b0db8fc74ac14fcd00ba8231371051dc2 | Vendor (CNA) |
| Linux Linux | 550ed693f47370502a71b85382e7f9e6417300b8 | Vendor (CNA) |
| Linux Linux | 713a40c892f40300d63691d9f85b2a23b48fe1e8 | Vendor (CNA) |
| Linux Linux | 78ad057472d8c76e0602402269222f9f9c698790 | Vendor (CNA) |
| Linux Linux | 84212387caadb211cd9dadd6fd5563bd37dc1f5e | Vendor (CNA) |
| Linux Linux | d02f30d220ef9511568a48dba8a9004c65f8d904 | Vendor (CNA) |
| debian:linux | 6.1.129-1 · Debian:12 | Package registry (OSV) |
| suse:kernel-default | 5.3.18-150300.59.235.1 · SUSE:Linux Enterprise Micro 5.2 | Package registry (OSV) |
| suse:kernel-default-base | 5.3.18-150300.59.235.1.150300.18.140.1 · SUSE:Linux Enterprise Micro 5.2 | Package registry (OSV) |
| suse:kernel-rt | 5.3.18-150300.235.1 · SUSE:Linux Enterprise Micro 5.2 | Package registry (OSV) |
| suse:kernel-source-rt | 5.3.18-150300.235.1 · SUSE:Linux Enterprise Micro 5.2 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
—
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (14 more)Show less
- git.kernel.org/stable/c/3c8ffcd248da34fc41e52a46e51505900115fc2a
- git.kernel.org/stable/c/4176a68b0db8fc74ac14fcd00ba8231371051dc2
- git.kernel.org/stable/c/550ed693f47370502a71b85382e7f9e6417300b8
- git.kernel.org/stable/c/713a40c892f40300d63691d9f85b2a23b48fe1e8
- git.kernel.org/stable/c/78ad057472d8c76e0602402269222f9f9c698790
- git.kernel.org/stable/c/84212387caadb211cd9dadd6fd5563bd37dc1f5e
- git.kernel.org/stable/c/d02f30d220ef9511568a48dba8a9004c65f8d904
- lists.debian.org/debian-lts-announce/2025/03/msg00028.html
- lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-082556.html
- cert-portal.siemens.com/productcert/html/ssa-265688.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
- cert-portal.siemens.com/productcert/html/ssa-784472.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.