CVE-2025-21765

MEDIUMNVD 5.55.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 5.5 from GitHub Security Advisory published 2025-02-27. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week
5.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 5.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity55% × 45%
The EG Score, 5.5 of 10.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.6%
EPSS %ILE
48th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

February 27, 2025

Last Modified

October 15, 2026

Advisory Details (10)

Auto-updated Jul 17, 2026
Patch available.
Web pageMentions a patch (unverified)

[SECURITY] [DLA 4178-1] linux security update

https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
Web pageMentions a patch (unverified)

[SECURITY] [DLA 4102-1] linux-6.1 security update

https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d02f30d220ef9511568a48dba8a9004c65f8d904
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/84212387caadb211cd9dadd6fd5563bd37dc1f5e
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/78ad057472d8c76e0602402269222f9f9c698790
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/713a40c892f40300d63691d9f85b2a23b48fe1e8
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/550ed693f47370502a71b85382e7f9e6417300b8
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4176a68b0db8fc74ac14fcd00ba8231371051dc2
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3c8ffcd248da34fc41e52a46e51505900115fc2a
Web page

ipv6: use RCU protection in ip6_default_advmss() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/28de355b63ad42309ed5a03ee7c436c90512265b

Vendor Advisories for CVE-2025-21765(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(31)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulinux-tools-fips (5.15.0.140.80) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gcp-fips (5.15.0.1083.73) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gcp-lts-22.04 (5.15.0.1083.79) @ jammy2026-05-21ubuntu
ubuntulinux-virtual-hwe-18.04-edge (5.4.0.216.208) @ focal2026-05-21ubuntu
ubuntulinux-tools-aws (6.11.0-1014.15) @ oracular2026-05-21ubuntu
ubuntulinux-virtual-hwe-18.04-edge (5.4.0.216.236~18.04.1) @ bionic2026-05-21ubuntu
ubuntulinux-tools-azure-fips (5.4.0.1151.88) @ focal2026-05-21ubuntu
ubuntulinux-tools-ibm-lts-20.04 (5.4.0.1092.121) @ focal2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.4.0-1064 (5.4.0-1064.68) @ focal2026-05-21ubuntu
ubuntulinux-tools-kvm (5.4.0.1133.129) @ focal2026-05-21ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-26.26) @ oracular2026-05-21ubuntu
ubuntulinux-tools-ibm-edge (5.4.0.1092.97~18.04.1) @ bionic2026-05-21ubuntu
ubuntulinux-tools-oracle-edge (5.4.0.1144.154~18.04.1) @ bionic2026-05-21ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1032.33) @ noble2026-05-21ubuntu
ubuntulinux-tools-realtime (5.15.0.1084.88) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gcp-fips (5.4.0.1149.91) @ focal2026-05-21ubuntu
ubuntulinux-tools-gke-5.15 (5.15.0.1081.80) @ jammy2026-05-21ubuntu
ubuntulinux-tools-azure-nvidia-lts-24.04 (6.8.0-1022.23) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-fips (5.15.0.1089.74) @ jammy2026-05-21ubuntu
ubuntulinux-tools-nvidia-tegra-rt (5.15.0.1037.37) @ jammy2026-05-21ubuntu
ubuntulinux-tools-raspi-6.8 (6.8.0-1035.39) @ noble2026-05-21ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2028.29) @ noble2026-05-21ubuntu
ubuntulinux-tools-ibm-lts-24.04 (6.8.0-1033.33) @ noble2026-05-21ubuntu
ubuntulinux-tools-oracle-64k (6.11.0-1016.17) @ oracular2026-05-21ubuntu
ubuntulinux-tools-raspi-nolpae (5.15.0.1078.76) @ jammy2026-05-21ubuntu
ubuntulinux-tools-bluefield (5.4.0.1105.101) @ focal2026-05-21ubuntu
ubuntulinux-tools-aws-fips (5.15.0.1084.80) @ jammy2026-05-21ubuntu
ubuntulinux-virtual-6.8 (6.8.0-78.78) @ noble2026-05-21ubuntu
redhatkernel-0:6.12.0-124.8.1.el10_12025-11-11redhat
redhatkernel-0:5.14.0-611.5.1.el9_72025-11-11redhat
linuxKernel @ 5.4.291 (fixes >=2.6.26)—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 5.10.92-2 (45 versions)
  • every version up to 5.10.237-1: fixed in 5.10.237-1
—
linux-6.16.1.106-3~deb11u1 ... 6.1.128-1~deb11u1 (6 versions)
  • every version up to 6.1.129-1~deb11u1: fixed in 6.1.129-1~deb11u1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (35 versions)
  • every version up to 6.1.129-1: fixed in 6.1.129-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.12.16-1: fixed in 6.12.16-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.12.16-1: fixed in 6.12.16-1
—

Additional Vendor Advisories

(23)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 16× in last 7d / 34× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 96 of 218 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 4 repeat rows among the latest 100 are merged into the row they repeat. The 122 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-15 02:54 UTCVendor advisory
  2. 2026-10-15 02:53 UTCGHSA enrichmentGHSA-cfq6-3hq6-2p95 · GitHub CVSS 5.5
  3. 2026-10-15 02:01 UTCEG score recompute
  4. 2026-10-15 02:01 UTCVendor advisory
  5. 2026-10-15 02:01 UTCGHSA enrichmentGHSA-cfq6-3hq6-2p95 · GitHub CVSS 5.5
  6. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  7. 2026-10-13 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  8. 2026-10-12 17:19 UTCEG score recompute
  9. 2026-10-12 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-10-11 20:51 UTCEG score recompute
  11. 2026-10-11 19:01 UTCEG score recompute
  12. 2026-10-11 15:41 UTCEG score recompute
  13. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  14. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  15. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  16. 2026-10-08 17:09 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  17. 2026-10-07 23:46 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  18. 2026-10-06 15:16 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  19. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  20. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  21. 2026-10-03 14:24 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  22. 2026-10-02 16:26 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  23. 2026-10-01 19:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  24. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  25. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile
Show 71 more
  1. 2026-09-28 02:02 UTCOSV refresh
  2. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-09-26 00:24 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  4. 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  5. 2026-09-23 13:46 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  6. 2026-09-22 14:47 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  7. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  8. 2026-09-16 14:06 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  9. 2026-09-16 05:13 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-09-15 03:09 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  11. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  12. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  13. 2026-09-11 14:51 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  14. 2026-09-11 09:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  15. 2026-09-10 09:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  16. 2026-09-08 21:59 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  17. 2026-09-08 09:52 UTCEG score recompute
  18. 2026-09-08 09:52 UTCVendor advisory
  19. 2026-09-08 09:51 UTCGHSA enrichmentGHSA-cfq6-3hq6-2p95 · GitHub CVSS 5.5
  20. 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  21. 2026-09-07 13:17 UTCOSV refresh
  22. 2026-09-06 13:46 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  23. 2026-09-05 15:28 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-09-04 05:05 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  25. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  26. 2026-09-01 13:52 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  27. 2026-09-01 04:38 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  28. 2026-08-30 19:16 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  29. 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  30. 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  31. 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  32. 2026-08-25 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  33. 2026-08-23 00:18 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  34. 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  35. 2026-08-20 22:54 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  36. 2026-08-20 22:31 UTCOSV refresh
  37. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  38. 2026-08-18 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  39. 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  40. 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  41. 2026-08-16 02:13 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  42. 2026-08-15 01:29 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  43. 2026-08-13 21:59 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  44. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  45. 2026-08-10 23:59 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  46. 2026-08-09 13:45 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  47. 2026-08-07 16:26 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  48. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  49. 2026-08-05 19:16 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  50. 2026-08-05 14:03 UTCEG score recompute
  51. 2026-08-05 14:03 UTCVendor advisory
  52. 2026-08-05 14:03 UTCGHSA enrichmentGHSA-cfq6-3hq6-2p95 · GitHub CVSS 5.5
  53. 2026-08-04 15:09 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  54. 2026-08-04 10:37 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  55. 2026-08-03 10:35 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  56. 2026-08-02 02:25 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  57. 2026-08-01 04:15 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  58. 2026-07-30 16:27 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  59. 2026-07-30 07:21 UTCEG score recompute
  60. 2026-07-30 07:21 UTCVendor advisory
  61. 2026-07-30 07:21 UTCGHSA enrichmentGHSA-cfq6-3hq6-2p95 · GitHub CVSS 5.5
  62. 2026-07-30 01:29 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  63. 2026-07-28 15:35 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  64. 2026-07-28 01:24 UTCOSV refresh
  65. 2026-07-27 14:12 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  66. 2026-07-26 14:53 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  67. 2026-07-25 14:17 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  68. 2026-07-24 14:17 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  69. 2026-07-23 14:17 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  70. 2026-07-23 02:50 UTCEG score recompute
  71. 2026-07-22 14:07 UTCEPSS rescoreEPSS 0.2% · 11th percentile

Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2025-21765?
CVE-2025-21765 is a medium-severity vulnerability; its CVE record was published on February 27, 2025. In the Linux kernel, the following vulnerability has been resolved: ipv6: use RCU protection in ip6defaultadvmss() ip6defaultadvmss() needs rcu protection to make sure the net structure it reads does not disappear.
When was the CVE record for CVE-2025-21765 published?
The CVE record for CVE-2025-21765 was published on February 27, 2025. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 15, 2026; the record at its source may have been updated since.
Is CVE-2025-21765 actively exploited?
CVE-2025-21765 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-21765?
CVE-2025-21765 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21765?
A fix for CVE-2025-21765 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2025-21765 are linked in the Vendor Advisories panel on this page.

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