CVE-2026-23455

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-04-03. NVD baseline CVSS 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

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

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()

In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read.

Add a check to ensure len is positive after the decrement.

CVSS v3
9.1
EG Score
9.1(medium)
EPSS
44.3%
KEV
Not listed

Published

April 3, 2026

Last Modified

July 14, 2026

Advisory Details (8)

Auto-updated May 2, 2026
No patch confirmed yet.
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4
generic

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0

Vendor Advisories for CVE-2026-23455(13)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:5.14.0-570.120.1.el9_62026-06-11redhat
redhatkernel-0:4.18.0-553.126.1.el8_102026-05-28redhat
redhatkernel-0:5.14.0-687.12.1.el9_82026-05-28redhat
redhatkernel-0:6.12.0-211.18.1.el10_22026-05-28redhat
redhatkernel-rt-0:4.18.0-553.126.1.rt7.467.el8_102026-05-28redhat

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 11× in last 7d / 49× 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 158 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-23455?
CVE-2026-23455 is a critical vulnerability published on April 3, 2026. In the Linux kernel, the following vulnerability has been resolved: netfilter: nfconntrackh323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to…
When was CVE-2026-23455 disclosed?
CVE-2026-23455 was first published in the National Vulnerability Database on April 3, 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-2026-23455 actively exploited?
CVE-2026-23455 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 44.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23455?
CVE-2026-23455 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-23455?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23455, 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.

Dependency Blast Radius

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