CVE-2026-50256

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. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. 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
5%
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

dix: increase XLFDMAXFONTNAMELEN to match libXfont2's MAXFONTNAMELEN (bb5158f9) · Commits · xorg / xserver · GitLab

https://gitlab.freedesktop.org/xorg/xserver/-/commit/bb5158f962dc935e58ef8b4b5fcb31be201a6e07
redhat

2485380 – (CVE-2026-50256) CVE-2026-50256 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libXfont2 name length mismatch

https://bugzilla.redhat.com/show_bug.cgi?id=2485380
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-50256

Vendor Advisories for CVE-2026-50256(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-0:1.12.0-6.el8_6.182026-07-27redhat
redhattigervnc-0:1.12.0-15.el8_8.182026-07-27redhat
redhattigervnc-0:1.12.0-14.el9_2.152026-07-27redhat
redhattigervnc-0:1.13.1-8.el9_4.102026-07-27redhat
redhattigervnc-0:1.14.1-11.el9_62026-07-27redhat
redhattigervnc-0:1.11.0-8.el8_4.162026-07-27redhat
redhattigervnc-0:1.8.0-36.el7_9.52026-07-27redhat
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-0:1.20.11-8.el8_62026-07-08redhat
redhatxorg-x11-server-0:1.20.11-19.el8_82026-07-08redhat
redhatxorg-x11-server-Xwayland-0:22.1.9-8.el9_4.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-10.el9_2.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:23.2.7-6.el9_6.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:24.1.5-6.el10_0.12026-07-08redhat
redhatxorg-x11-server-0:1.20.10-5.el8_42026-07-08redhat
redhatxorg-x11-server-0:1.20.11-34.el9_62026-07-07redhat
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-0:1.20.11-29.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-0:1.20.11-34.el9_8.22026-06-17redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.22026-06-17redhat
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

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 / 50× 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 379 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 00:31 UTCVendor advisory
  25. 2026-08-24 00:31 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 00:50 UTCEG score recompute
  6. 2026-08-22 00:50 UTCVendor advisory
  7. 2026-08-22 00:50 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 21:45 UTCVendor advisory
  14. 2026-08-20 21:45 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 15:38 UTCEG score recompute
  21. 2026-08-17 15:38 UTCVendor advisory
  22. 2026-08-17 15:38 UTCGHSA enrichment
  23. 2026-08-17 13:47 UTCEPSS rescore
  24. 2026-08-17 03:33 UTCVendor advisory
  25. 2026-08-17 03:33 UTCGHSA enrichment
  26. 2026-08-16 15:28 UTCEG score recompute
  27. 2026-08-16 15:28 UTCVendor advisory
  28. 2026-08-16 15:28 UTCGHSA enrichment
  29. 2026-08-16 14:56 UTCEPSS rescore
  30. 2026-08-16 03:25 UTCEG score recompute
  31. 2026-08-16 03:25 UTCVendor advisory
  32. 2026-08-16 03:25 UTCGHSA enrichment
  33. 2026-08-16 02:14 UTCEPSS rescore
  34. 2026-08-15 15:22 UTCVendor advisory
  35. 2026-08-15 15:22 UTCGHSA enrichment
  36. 2026-08-15 03:18 UTCEG score recompute
  37. 2026-08-15 03:18 UTCVendor advisory
  38. 2026-08-15 03:18 UTCGHSA enrichment
  39. 2026-08-15 01:30 UTCEPSS rescore
  40. 2026-08-14 15:14 UTCVendor advisory
  41. 2026-08-14 15:14 UTCGHSA enrichment
  42. 2026-08-14 03:11 UTCEG score recompute
  43. 2026-08-14 03:11 UTCVendor advisory
  44. 2026-08-14 03:11 UTCGHSA enrichment
  45. 2026-08-13 22:00 UTCEPSS rescore
  46. 2026-08-13 15:08 UTCVendor advisory
  47. 2026-08-13 15:08 UTCGHSA enrichment
  48. 2026-08-13 02:50 UTCVendor advisory
  49. 2026-08-13 02:50 UTCGHSA enrichment
  50. 2026-08-12 14:48 UTCEG score recompute
  51. 2026-08-12 14:48 UTCVendor advisory
  52. 2026-08-12 14:48 UTCGHSA enrichment
  53. 2026-08-12 13:51 UTCEPSS rescore
  54. 2026-08-12 02:43 UTCVendor advisory
  55. 2026-08-12 02:43 UTCGHSA enrichment
  56. 2026-08-11 14:40 UTCEG score recompute
  57. 2026-08-11 14:40 UTCVendor advisory
  58. 2026-08-11 14:40 UTCGHSA enrichment
  59. 2026-08-11 02:30 UTCEG score recompute
  60. 2026-08-11 02:30 UTCVendor advisory
  61. 2026-08-11 02:29 UTCGHSA enrichment
  62. 2026-08-11 00:00 UTCEPSS rescore
  63. 2026-08-10 14:27 UTCVendor advisory
  64. 2026-08-10 14:27 UTCGHSA enrichment
  65. 2026-08-10 02:23 UTCVendor advisory
  66. 2026-08-10 02:23 UTCGHSA enrichment
  67. 2026-08-09 14:20 UTCEG score recompute
  68. 2026-08-09 14:20 UTCVendor advisory
  69. 2026-08-09 14:20 UTCGHSA enrichment
  70. 2026-08-09 13:46 UTCEPSS rescore
  71. 2026-08-09 02:18 UTCEG score recompute
  72. 2026-08-09 02:18 UTCVendor advisory
  73. 2026-08-09 02:18 UTCGHSA enrichment
  74. 2026-08-08 16:37 UTCEPSS rescore
  75. 2026-08-08 14:15 UTCVendor advisory

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-50256?
CVE-2026-50256 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. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias…
When was CVE-2026-50256 disclosed?
CVE-2026-50256 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-2026-50256 actively exploited?
CVE-2026-50256 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 94.8% of all scored CVEs.
What is the CVSS score of CVE-2026-50256?
CVE-2026-50256 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-50256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-50256, 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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