CVE-2026-23398

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2026-03-26. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

icmp: fix NULL pointer dereference in icmp_tag_validation()

icmp_tag_validation() unconditionally dereferences the result of rcu_dereference(inet_protos[proto]) without checking for NULL. The inet_protos[] array is sparse -- only about 15 of 256 protocol numbers have registered handlers. When ip_no_pmtu_disc is set to 3 (hardened PMTU mode) and the kernel receives an ICMP Fragmentation Needed error with a quoted inner IP header containing an unregistered protocol number, the NULL dereference causes a kernel panic in softirq context.

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143) Call Trace: icmp_rcv (net/ipv4/icmp.c:1527) ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207) ip_local_deliver_finish (net/ipv4/ip_input.c:242) ip_local_deliver (net/ipv4/ip_input.c:262) ip_rcv (net/ipv4/ip_input.c:573) __netif_receive_skb_one_core (net/core/dev.c:6164) process_backlog (net/core/dev.c:6628) handle_softirqs (kernel/softirq.c:561)

Add a NULL check before accessing icmp_strict_tag_validation. If the protocol has no registered handler, return false since it cannot perform strict tag validation.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

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
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

March 26, 2026

Last Modified

July 14, 2026

Advisory Details (10)

Auto-updated Jul 19, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic🔴 Active Exploitation

SSA-082556

https://cert-portal.siemens.com/productcert/html/ssa-082556.html
generic

SSA-019113

https://cert-portal.siemens.com/productcert/html/ssa-019113.html
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d938dd5a0ad780c891ea3bc94cae7405f11e618a
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d783fa413c702ff0f8f8bea63f862e28eeaf39e3
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b61529c357f1ee4d64836eb142a542d2e7ad67ce
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9647e99d2a617c355d2b378be0ff6d0e848fd579
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/614aefe56af8e13331e50220c936fc0689cf5675
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/571d9d7b650f02d1e38c01128817868bceac9edd
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161
generic

icmp: fix NULL pointer dereference in icmp_tag_validation() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1e4e2f5e48cec0cccaea9815fb9486c084ba41e2

Vendor Advisories for CVE-2026-23398(2)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
linuxKernel @ 5.10.253—osv
linuxKernel @ 6.1.167—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.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 44× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 140 total refreshes for this CVE.

  1. 2026-07-30 01:30 UTCEPSS rescore
  2. 2026-07-27 14:13 UTCEPSS rescore
  3. 2026-07-26 14:54 UTCEPSS rescore
  4. 2026-07-26 14:54 UTCEPSS rescore
  5. 2026-07-25 14:17 UTCEPSS rescore
  6. 2026-07-25 14:17 UTCEPSS rescore
  7. 2026-07-24 14:17 UTCEPSS rescore
  8. 2026-07-23 14:18 UTCEPSS rescore
  9. 2026-07-23 14:18 UTCEPSS rescore
  10. 2026-07-23 03:07 UTCEG score recompute
  11. 2026-07-22 14:08 UTCEPSS rescore
  12. 2026-07-21 15:24 UTCEPSS rescore
  13. 2026-07-21 15:24 UTCEPSS rescore
  14. 2026-07-20 17:08 UTCEPSS rescore
  15. 2026-07-19 14:31 UTCEPSS rescore
  16. 2026-07-19 14:31 UTCEPSS rescore
  17. 2026-07-19 02:29 UTCEPSS rescore
  18. 2026-07-19 02:28 UTCEPSS rescore
  19. 2026-07-17 05:24 UTCOSV refresh
  20. 2026-07-16 17:03 UTCEPSS rescore
  21. 2026-07-16 17:03 UTCEPSS rescore
  22. 2026-07-15 16:57 UTCEPSS rescore
  23. 2026-07-15 16:57 UTCEPSS rescore
  24. 2026-07-15 02:00 UTCEPSS rescore
  25. 2026-07-15 02:00 UTCEPSS rescore
Show 75 more
  1. 2026-07-14 13:19 UTCNVD updateCVSS v3 → 5.5 · severity → MEDIUM
  2. 2026-07-14 13:11 UTCMITRE cvelistV5
  3. 2026-07-13 22:30 UTCEPSS rescore
  4. 2026-07-13 06:13 UTCEPSS rescore
  5. 2026-07-13 06:13 UTCEPSS rescore
  6. 2026-07-12 05:46 UTCEPSS rescore
  7. 2026-07-12 05:46 UTCEPSS rescore
  8. 2026-07-11 08:27 UTCEPSS rescore
  9. 2026-07-09 19:10 UTCEPSS rescore
  10. 2026-07-08 15:15 UTCEPSS rescore
  11. 2026-07-08 15:15 UTCEPSS rescore
  12. 2026-07-07 13:46 UTCEPSS rescore
  13. 2026-07-06 16:27 UTCEPSS rescore
  14. 2026-07-06 16:27 UTCEPSS rescore
  15. 2026-07-06 02:23 UTCEPSS rescore
  16. 2026-07-06 02:23 UTCEPSS rescore
  17. 2026-07-05 02:30 UTCEPSS rescore
  18. 2026-07-04 06:31 UTCEPSS rescore
  19. 2026-07-04 06:31 UTCEPSS rescore
  20. 2026-07-01 15:06 UTCEPSS rescore
  21. 2026-07-01 15:06 UTCEPSS rescore
  22. 2026-06-30 23:22 UTCEPSS rescore
  23. 2026-06-30 23:22 UTCEPSS rescore
  24. 2026-06-29 14:06 UTCEPSS rescore
  25. 2026-06-29 03:32 UTCOSV refresh
  26. 2026-06-28 14:07 UTCEPSS rescore
  27. 2026-06-28 14:07 UTCEPSS rescore
  28. 2026-06-28 04:56 UTCEPSS rescore
  29. 2026-06-28 04:56 UTCEPSS rescore
  30. 2026-06-27 03:08 UTCEPSS rescore
  31. 2026-06-25 13:49 UTCEPSS rescore
  32. 2026-06-25 13:49 UTCEPSS rescore
  33. 2026-06-24 14:05 UTCEPSS rescore
  34. 2026-06-24 14:05 UTCEPSS rescore
  35. 2026-06-23 21:33 UTCEPSS rescore
  36. 2026-06-23 21:32 UTCEPSS rescore
  37. 2026-06-22 14:25 UTCEPSS rescore
  38. 2026-06-22 14:25 UTCEPSS rescore
  39. 2026-06-21 14:56 UTCEPSS rescore
  40. 2026-06-21 14:56 UTCEPSS rescore
  41. 2026-06-21 01:59 UTCEPSS rescore
  42. 2026-06-21 01:59 UTCEPSS rescore
  43. 2026-06-19 19:25 UTCEPSS rescore
  44. 2026-06-19 19:25 UTCEPSS rescore
  45. 2026-06-18 17:52 UTCEPSS rescore
  46. 2026-06-17 17:53 UTCEPSS rescore
  47. 2026-06-17 17:53 UTCEPSS rescore
  48. 2026-06-16 17:52 UTCEPSS rescore
  49. 2026-06-15 17:48 UTCEPSS rescore
  50. 2026-06-14 23:18 UTCEPSS rescore
  51. 2026-06-13 23:00 UTCEPSS rescore
  52. 2026-06-12 23:12 UTCEPSS rescore
  53. 2026-06-12 23:12 UTCEPSS rescore
  54. 2026-06-11 23:22 UTCVendor advisory
  55. 2026-06-11 23:22 UTCGHSA enrichment
  56. 2026-06-11 14:00 UTCEPSS rescore
  57. 2026-06-10 22:18 UTCEPSS rescore
  58. 2026-06-10 14:48 UTCVendor advisory
  59. 2026-06-10 14:48 UTCGHSA enrichment
  60. 2026-06-10 13:22 UTCEPSS rescore
  61. 2026-06-09 15:33 UTCVendor advisory
  62. 2026-06-09 15:33 UTCGHSA enrichment
  63. 2026-06-08 14:17 UTCEPSS rescore
  64. 2026-06-08 14:17 UTCEPSS rescore
  65. 2026-06-08 13:25 UTCVendor advisory
  66. 2026-06-08 13:25 UTCGHSA enrichment
  67. 2026-06-07 15:25 UTCEPSS rescore
  68. 2026-06-07 15:24 UTCEPSS rescore
  69. 2026-06-07 12:04 UTCVendor advisory
  70. 2026-06-07 12:04 UTCGHSA enrichment
  71. 2026-06-06 13:47 UTCEPSS rescore
  72. 2026-06-06 13:47 UTCEPSS rescore
  73. 2026-06-06 13:47 UTCEPSS rescore
  74. 2026-06-05 22:47 UTCEPSS rescore
  75. 2026-06-05 06:10 UTCEPSS rescore

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-23398?
CVE-2026-23398 is a medium vulnerability published on March 26, 2026. In the Linux kernel, the following vulnerability has been resolved: icmp: fix NULL pointer dereference in icmptagvalidation() icmptagvalidation() unconditionally dereferences the result of rcudereference(inetprotos[proto]) without checking for NULL. The inet_protos[] array is sparse -- only about…
When was CVE-2026-23398 disclosed?
CVE-2026-23398 was first published in the National Vulnerability Database on March 26, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23398 actively exploited?
CVE-2026-23398 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 97.9% of all scored CVEs.
What is the CVSS score of CVE-2026-23398?
CVE-2026-23398 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-23398?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23398, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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