CVE-2026-40355

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.6%, top 53% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, causing the process to terminate in parse_nego_message.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
50
EG Risk 50/100

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
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
EPSS PROB
0.8%
EPSS %ILE
55th
KEV
Not listed

Published

April 28, 2026

Last Modified

September 8, 2026

Advisory Details (3)

Auto-updated Jun 14, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit.
generic🟡 PoC Available

Advisory - Kerberos (krb5) Two Unauthenticated Network Vulnerabilities: CVE-2026-40355 & CVE-2026-40356 | Cem’s Blog

https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
generic

Kerberos Security Advisories

https://web.mit.edu/kerberos/advisories/
github_commit

commit 2e75f0d9362f (krb5/krb5)

Fix landed in krb5/krb5 commit 2e75f0d9362f — awaiting tagged release

https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f

Vendor Advisories for CVE-2026-40355(11)

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

Patch Availability(9)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibkrb5support0 (1.20.1-6ubuntu2.7) @ noble2026-09-08ubuntu
redhatrhui5/rhua-tp-rhel9:17872412602026-08-24redhat
redhatdiscovery/discovery-ui-rhel9:17821669522026-06-24redhat
redhatinsights-proxy/insights-proxy-container-rhel9:17804204282026-06-02redhat
redhatrhui5/rhua-rhel9:17797982222026-05-27redhat
redhatkrb5-0:1.21.3-10.el10_22026-05-19redhat
redhatkrb5-0:1.21.1-10.el9_82026-05-19redhat
redhatkrb5-0:1.18.2-34.el8_102026-05-13redhat
redhatkrb5-main-1.22.2-7.hum12026-04-30redhat

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
krb51.18.3-6 ... 1.18.3-6+deb11u7 (8 versions)
  • every version up to 1.18.3-6+deb11u8: fixed in 1.18.3-6+deb11u8
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
krb51.20.1-2, 1.20.1-2+deb12u1, 1.20.1-2+deb12u2, 1.20.1-2+deb12u3, 1.20.1-2+deb12u4
  • every version up to 1.20.1-2+deb12u5: fixed in 1.20.1-2+deb12u5
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
krb51.21.3-5
  • every version up to 1.21.3-5+deb13u1: fixed in 1.21.3-5+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
krb51.21.3-5, 1.22.1-1, 1.22.1-2
  • every version up to 1.22.1-2.1: fixed in 1.22.1-2.1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

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 7× in last 7d / 22× 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 245 total refreshes for this CVE.

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

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

Frequently asked(5)

What is CVE-2026-40355?
CVE-2026-40355 is a high vulnerability published on April 28, 2026. In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gssacceptseccontext() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, causing the process to terminate in parsenego_message.
When was CVE-2026-40355 disclosed?
CVE-2026-40355 was first published on April 28, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40355 actively exploited?
CVE-2026-40355 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (55th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-40355?
CVE-2026-40355 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-40355?
A fix for CVE-2026-40355 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-40355 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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