CVE-2026-90237

HIGHPre-NVD 7.87.8—
EchelonGraph scoreHIGH confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-09-17. A secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
7.8EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: None knownExposed services: Not assessed

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

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

netfilter: nft_ct: move custom expectation support to helper

Originally, the ct expectation support called nf_ct_helper_ext_add() for confirmed conntracks, which is invalid, triggering a splat. This was fixed by commit 1710eb913bdc ("netfilter: nft_ct: skip expectations for confirmed conntrack") which restricted it to unconfirmed conntracks.

However, early insertion of expectations into the expectations list when the conntrack is unconfirmed leads to stale entries pointing to the wrong hlist_head through .pprev due to ct extension reallocation.

Commit 7c9664351980 ("netfilter: move nat hlist_head to nf_conn") moved the nat hlist_head to nf_conn for this reason:

  • ...
  • When reallocation of extension area occurs we need to fixup the
bysource hash head via hlist_replace_rcu.

I'd rather not increase the size of the struct nf_conn for this feature has very limited scope: only one expectation can be created at a time given expect_clash() will make nf_ct_expect_related() reports EBUSY. For this reason, relax nf_ct_expect_related() not to drop packets in case expectation creation fails, therefore, expectation creation becomes best effort.

To address this issue, add an internal ct helper and attach it to the conntrack entry to streamline the custom ct expectation support with existing ct helpers.

Expose a new nf_conntrack_helper_release() function to release the internal helper that is allocated and attached to the conntrack entry to create the custom expectations. The nft_ct module removal always waits for rcu grace period, then the NULL helper callback is observed after this.

This patch also restricts the creation of expectations to different helpers other than this custom helper that is created for this type of expectations.

CVSS v3
7.8
EG Score
7.8HIGHhigh confidence
EG Risk
40
EG Risk 40/100CISA SSVC

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
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
5th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 17, 2026

Last Modified

September 18, 2026

Advisory Details (2)

Auto-updated Sep 18, 2026
No patch confirmed yet.
generic

netfilter: nft_ct: move custom expectation support to helper - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/af3fe52fd108fd38235e4813df62442ed0f1d8ff
generic

netfilter: nft_ct: move custom expectation support to helper - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3679da4ad8be84cddaf40bc307fef1fe13e051ff

Vendor Advisories for CVE-2026-90237(2)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (358 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (181 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (178 versions)
  • every version up to 7.2.6-1: fixed in 7.2.6-1
—

Data Freshness Timeline

(refreshed 38× in last 7d / 98× 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.

  1. 2026-10-05 00:47 UTCEG score recompute
  2. 2026-10-05 00:47 UTCVendor advisory
  3. 2026-10-05 00:47 UTCGHSA enrichment
  4. 2026-10-04 23:22 UTCEPSS rescore
  5. 2026-10-04 11:49 UTCVendor advisory
  6. 2026-10-04 11:49 UTCGHSA enrichment
  7. 2026-10-03 22:55 UTCEG score recompute
  8. 2026-10-03 22:55 UTCVendor advisory
  9. 2026-10-03 22:55 UTCGHSA enrichment
  10. 2026-10-03 10:00 UTCVendor advisory
  11. 2026-10-03 10:00 UTCGHSA enrichment
  12. 2026-10-02 20:44 UTCEG score recompute
  13. 2026-10-02 20:44 UTCVendor advisory
  14. 2026-10-02 20:44 UTCGHSA enrichment
  15. 2026-10-02 07:49 UTCEG score recompute
  16. 2026-10-02 07:49 UTCVendor advisory
  17. 2026-10-02 07:49 UTCGHSA enrichment
  18. 2026-10-01 19:51 UTCEPSS rescore
  19. 2026-10-01 18:52 UTCVendor advisory
  20. 2026-10-01 18:52 UTCGHSA enrichment
  21. 2026-10-01 05:48 UTCVendor advisory
  22. 2026-10-01 05:48 UTCGHSA enrichment
  23. 2026-09-30 16:53 UTCEG score recompute
  24. 2026-09-30 16:53 UTCVendor advisory
  25. 2026-09-30 16:53 UTCGHSA enrichment
Show 73 more
  1. 2026-09-30 15:04 UTCEPSS rescore
  2. 2026-09-30 02:44 UTCEG score recompute
  3. 2026-09-30 02:44 UTCVendor advisory
  4. 2026-09-30 02:44 UTCGHSA enrichment
  5. 2026-09-29 13:49 UTCVendor advisory
  6. 2026-09-29 13:49 UTCGHSA enrichment
  7. 2026-09-29 00:54 UTCEG score recompute
  8. 2026-09-29 00:54 UTCVendor advisory
  9. 2026-09-29 00:54 UTCGHSA enrichment
  10. 2026-09-28 13:52 UTCEPSS rescore
  11. 2026-09-28 13:52 UTCEPSS rescore
  12. 2026-09-28 11:59 UTCVendor advisory
  13. 2026-09-28 11:59 UTCGHSA enrichment
  14. 2026-09-27 23:04 UTCEG score recompute
  15. 2026-09-27 23:04 UTCVendor advisory
  16. 2026-09-27 23:04 UTCGHSA enrichment
  17. 2026-09-27 13:49 UTCEPSS rescore
  18. 2026-09-27 10:08 UTCVendor advisory
  19. 2026-09-27 10:08 UTCGHSA enrichment
  20. 2026-09-26 21:13 UTCEG score recompute
  21. 2026-09-26 21:13 UTCVendor advisory
  22. 2026-09-26 21:13 UTCGHSA enrichment
  23. 2026-09-26 15:59 UTCEPSS rescore
  24. 2026-09-26 08:18 UTCEG score recompute
  25. 2026-09-26 08:18 UTCVendor advisory
  26. 2026-09-26 08:18 UTCGHSA enrichment
  27. 2026-09-25 19:19 UTCVendor advisory
  28. 2026-09-25 19:19 UTCGHSA enrichment
  29. 2026-09-25 05:41 UTCVendor advisory
  30. 2026-09-25 05:41 UTCGHSA enrichment
  31. 2026-09-24 16:46 UTCEG score recompute
  32. 2026-09-24 16:46 UTCVendor advisory
  33. 2026-09-24 16:46 UTCGHSA enrichment
  34. 2026-09-24 14:04 UTCEPSS rescore
  35. 2026-09-24 03:51 UTCEG score recompute
  36. 2026-09-24 03:51 UTCVendor advisory
  37. 2026-09-24 03:51 UTCGHSA enrichment
  38. 2026-09-23 17:54 UTCEPSS rescore
  39. 2026-09-23 14:46 UTCVendor advisory
  40. 2026-09-23 14:46 UTCGHSA enrichment
  41. 2026-09-23 01:52 UTCEG score recompute
  42. 2026-09-23 01:52 UTCVendor advisory
  43. 2026-09-23 01:52 UTCGHSA enrichment
  44. 2026-09-22 16:01 UTCEPSS rescore
  45. 2026-09-22 12:56 UTCVendor advisory
  46. 2026-09-22 12:56 UTCGHSA enrichment
  47. 2026-09-22 00:01 UTCEG score recompute
  48. 2026-09-22 00:01 UTCVendor advisory
  49. 2026-09-22 00:01 UTCGHSA enrichment
  50. 2026-09-21 21:09 UTCEPSS rescore
  51. 2026-09-21 11:06 UTCVendor advisory
  52. 2026-09-21 11:06 UTCGHSA enrichment
  53. 2026-09-20 22:12 UTCEG score recompute
  54. 2026-09-20 22:12 UTCVendor advisory
  55. 2026-09-20 22:12 UTCGHSA enrichment
  56. 2026-09-20 20:16 UTCEPSS rescore
  57. 2026-09-20 09:17 UTCVendor advisory
  58. 2026-09-20 09:17 UTCGHSA enrichment
  59. 2026-09-19 20:20 UTCEG score recompute
  60. 2026-09-19 20:20 UTCVendor advisory
  61. 2026-09-19 20:20 UTCGHSA enrichment
  62. 2026-09-19 07:25 UTCEG score recompute
  63. 2026-09-19 07:25 UTCVendor advisory
  64. 2026-09-19 07:25 UTCGHSA enrichment
  65. 2026-09-18 19:28 UTCEPSS rescore
  66. 2026-09-18 18:30 UTCEG score recompute
  67. 2026-09-18 18:30 UTCGHSA enrichment
  68. 2026-09-18 18:04 UTCEG score recompute▲ 7.80
  69. 2026-09-18 18:03 UTCGHSA enrichment
  70. 2026-09-18 17:59 UTCMITRE cvelistV5CVSS v3 → 7.8 · severity → HIGH
  71. 2026-09-17 17:24 UTCNVD update
  72. 2026-09-17 16:38 UTCEG score recompute
  73. 2026-09-17 16:19 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-90237?
CVE-2026-90237 is a high vulnerability published on September 17, 2026. In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: move custom expectation support to helper Originally, the ct expectation support called nfcthelperextadd() for confirmed conntracks, which is invalid, triggering a splat. This was fixed by commit 1710eb913bdc…
When was CVE-2026-90237 disclosed?
CVE-2026-90237 was first published on September 17, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-90237 actively exploited?
CVE-2026-90237 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-90237?
CVE-2026-90237 has a CVSS base score of 7.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-90237?
No fix for CVE-2026-90237 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-90237 are linked in the Vendor Advisories panel on this page.

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