CVE-2026-50258

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-06-05. a secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 5 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

A fix is available — apply it.

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

June 5, 2026

Last Modified

August 5, 2026

Advisory Details (5)

Auto-updated Jun 5, 2026
Patch available. Sources: redhat.
generic

Jira

https://redhat.atlassian.net/browse/PSIRTSUPT-16950
generic

X.Org Security Advisory: multiple security issues X.Org X server and Xwayland

https://lists.x.org/archives/xorg-announce/2026-June/003702.html
generic

xkb: reject key types with num_levels exceeding XkbMaxShiftLevel (543e1085) · Commits · xorg / xserver · GitLab

https://gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e
redhat

2485383 – (CVE-2026-50258) CVE-2026-50258 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB key types due to unchecked shift levels

https://bugzilla.redhat.com/show_bug.cgi?id=2485383
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-50258

Vendor Advisories for CVE-2026-50258(20)

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

Patch Availability(28)

Vendor / EcosystemFixed in / PatchReleasedSource
redhattigervnc-0:1.1.0-25.el6_10.182026-08-03redhat
redhattigervnc-0:1.11.0-8.el8_4.162026-07-27redhat
redhattigervnc-0:1.12.0-6.el8_6.182026-07-27redhat
redhattigervnc-0:1.12.0-15.el8_8.182026-07-27redhat
redhattigervnc-0:1.13.1-8.el9_4.102026-07-27redhat
redhattigervnc-0:1.14.1-11.el9_62026-07-27redhat
redhattigervnc-0:1.8.0-36.el7_9.52026-07-27redhat
redhattigervnc-0:1.12.0-14.el9_2.152026-07-27redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-2.el8_6.72026-07-13redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-13.el8_8.12026-07-13redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-10.el9_2.12026-07-08redhat
redhatxorg-x11-server-0:1.20.10-5.el8_42026-07-08redhat
redhatxorg-x11-server-0:1.20.11-19.el8_82026-07-08redhat
redhatxorg-x11-server-0:1.20.11-8.el8_62026-07-08redhat
redhatxorg-x11-server-Xwayland-0:24.1.5-6.el10_0.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:22.1.9-8.el9_4.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:23.2.7-6.el9_6.12026-07-08redhat
redhatxorg-x11-server-0:1.20.4-35.el7_92026-07-07redhat
redhatxorg-x11-server-0:1.20.11-21.el9_22026-07-07redhat
redhatxorg-x11-server-0:1.20.11-34.el9_62026-07-07redhat
redhatxorg-x11-server-0:1.20.11-29.el9_42026-07-07redhat
redhattigervnc-0:1.15.0-7.el9_8.22026-06-25redhat
redhattigervnc-0:1.15.0-10.el8_102026-06-24redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el10_2.22026-06-22redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-20.el8_10.22026-06-17redhat
redhatxorg-x11-server-0:1.20.11-28.el8_10.22026-06-17redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.22026-06-17redhat
redhatxorg-x11-server-0:1.20.11-34.el9_8.22026-06-17redhat

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

(7 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.7-3 ... 2:21.1.7-3+deb12u9 (13 versions)2:21.1.7-3+deb12u13—
xwayland2:22.1.9-1 ... 2:24.1.9-1 (24 versions)——
Debian:13(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.16-1.3, 2:21.1.16-1.3+deb13u1, 2:21.1.16-1.3+deb13u22:21.1.16-1.3+deb13u3—
xwayland2:24.1.10-1 ... 2:24.1.9-1 (7 versions)——
Debian:14(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.16-1.3 ... 2:21.1.22-1 (6 versions)2:21.1.23-1—
xwayland2:24.1.10-1, 2:24.1.11-1, 2:24.1.6-1, 2:24.1.8-1, 2:24.1.9-12:24.1.12-1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
xorg-server2:1.20.11-1 ... 2:21.1.9-1+hurd.1 (62 versions)——

Weakness Classification(1)

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

Additional Vendor Advisories

(7)

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 / 51× 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 378 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-50258?
CVE-2026-50258 is a high vulnerability published on June 5, 2026. A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive…
When was CVE-2026-50258 disclosed?
CVE-2026-50258 was first published in the National Vulnerability Database on June 5, 2026, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-50258 actively exploited?
CVE-2026-50258 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 94.3% of all scored CVEs.
What is the CVSS score of CVE-2026-50258?
CVE-2026-50258 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-50258?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-50258, 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-2026-50258

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