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: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

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
7.5(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: 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
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
48%
KEV
Not listed

Published

April 28, 2026

Last Modified

September 8, 2026

Advisory Details (3)

Auto-updated Jun 14, 2026
🔬 Proof of concept available. Upstream fix merged — awaiting tagged release. 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(10)

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 / EcosystemFixed in / 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 rangeFixed inDependents
krb51.18.3-6 ... 1.18.3-6+deb11u7 (8 versions)1.18.3-6+deb11u8—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
krb51.20.1-2, 1.20.1-2+deb12u1, 1.20.1-2+deb12u2, 1.20.1-2+deb12u3, 1.20.1-2+deb12u41.20.1-2+deb12u5—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
krb51.21.3-51.21.3-5+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
krb51.21.3-5, 1.22.1-1, 1.22.1-21.22.1-2.1—

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 / 31× 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 233 total refreshes for this CVE.

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

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 in the National Vulnerability Database 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 1% probability of exploitation in the next 30 days, which ranks it in the top 52.1% of all 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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40355, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-40355

Explore →

Is Your Infrastructure Affected by CVE-2026-40355?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs