CVE-2026-50256

HIGHPre-NVD 7.87.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-06-05. The CNA's CVSS baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: the CNA's CVSS, EPSS, GitHub Security Advisory
Trending — 4 sources updated this week

Also known asEUVD-2026-34813 (ENISA EUVD) · GHSA-7gx3-r5q9-6j33 (GitHub Security Advisories)Source: ENISA EUVD

7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: None knownExposed services: Not assessed

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
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
4th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 5, 2026

Last Modified

September 28, 2026

Advisory Details (5)

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

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

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

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

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

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
Red HatMentions a patch (unverified)

cve-details

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

Patch Availability(28)

Vendor / EcosystemFix (by version range) / 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 rangeFix by version rangeDependents
xorg-server2:21.1.7-3 ... 2:21.1.7-3+deb12u9 (13 versions)
  • every version up to 2:21.1.7-3+deb12u13: fixed in 2:21.1.7-3+deb12u13
—
xwayland2:22.1.9-1 ... 2:24.1.9-1 (24 versions)
  • every version on: no fix on record
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
xorg-server2:21.1.16-1.3, 2:21.1.16-1.3+deb13u1, 2:21.1.16-1.3+deb13u2
  • every version up to 2:21.1.16-1.3+deb13u3: fixed in 2:21.1.16-1.3+deb13u3
—
xwayland2:24.1.10-1 ... 2:24.1.9-1 (7 versions)
  • every version on: no fix on record
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
xorg-server2:21.1.16-1.3 ... 2:21.1.22-1 (6 versions)
  • every version up to 2:21.1.23-1: fixed in 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, 2:24.1.9-1
  • every version up to 2:24.1.12-1: fixed in 2:24.1.12-1
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
xorg-server2:1.20.11-1 ... 2:21.1.9-1+hurd.1 (62 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

Additional Vendor Advisories

(7)

Data Freshness Timeline

(refreshed 11× in last 7d / 42× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 434 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 334 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  2. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  3. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  4. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  5. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  6. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  7. 2026-10-25 14:22 UTCEG score recompute
  8. 2026-10-25 02:12 UTCEG score recompute
  9. 2026-10-25 02:12 UTCVendor advisory
  10. 2026-10-25 02:12 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  11. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  12. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  13. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  14. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  16. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  17. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  18. 2026-10-18 03:33 UTCEG score recompute
  19. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  20. 2026-10-17 11:48 UTCEG score recompute
  21. 2026-10-17 11:48 UTCVendor advisory
  22. 2026-10-17 11:48 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  23. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  24. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  25. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
Show 75 more
  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  3. 2026-10-12 15:59 UTCEG score recompute
  4. 2026-10-11 19:42 UTCEG score recompute
  5. 2026-10-11 16:57 UTCEG score recompute
  6. 2026-10-11 14:21 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  12. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  13. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  14. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  15. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  16. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  17. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  18. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  19. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  20. 2026-09-28 11:57 UTCEG score recompute
  21. 2026-09-28 11:57 UTCVendor advisory
  22. 2026-09-28 11:57 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  23. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  24. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  25. 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  26. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  27. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  28. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  29. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  30. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  31. 2026-09-14 05:03 UTCEG score recompute
  32. 2026-09-14 05:03 UTCVendor advisory
  33. 2026-09-14 05:03 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  34. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  35. 2026-09-12 21:06 UTCOSV refresh
  36. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  37. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  38. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  39. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  40. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  41. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  42. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  43. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  44. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  45. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  46. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  47. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  48. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  49. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  50. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  51. 2026-08-25 02:03 UTCEG score recompute
  52. 2026-08-25 02:03 UTCVendor advisory
  53. 2026-08-25 02:03 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  54. 2026-08-24 00:31 UTCVendor advisory
  55. 2026-08-24 00:31 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  56. 2026-08-23 12:28 UTCEG score recompute
  57. 2026-08-23 12:28 UTCVendor advisory
  58. 2026-08-23 12:28 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  59. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  60. 2026-08-22 00:50 UTCEG score recompute
  61. 2026-08-22 00:50 UTCVendor advisory
  62. 2026-08-22 00:50 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  63. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  64. 2026-08-21 12:47 UTCEG score recompute
  65. 2026-08-21 12:47 UTCVendor advisory
  66. 2026-08-21 12:47 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  67. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  68. 2026-08-20 21:45 UTCVendor advisory
  69. 2026-08-20 21:45 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  70. 2026-08-20 09:42 UTCEG score recompute
  71. 2026-08-20 09:42 UTCVendor advisory
  72. 2026-08-20 09:42 UTCGHSA enrichmentGHSA-7gx3-r5q9-6j33 · GitHub severity HIGH · GitHub CVSS 7.8
  73. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  74. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  75. 2026-08-17 15:38 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-50256?
CVE-2026-50256 is a high-severity vulnerability; its CVE record was 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 made public?
CVE-2026-50256 was made public on June 2, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on June 5, 2026. EchelonGraph's copy of the record carries a last-modified date of September 28, 2026; the record at its source may have been updated since.
Is CVE-2026-50256 actively exploited?
CVE-2026-50256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (4th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-50256?
CVE-2026-50256 has a CVSS base score of 7.8 (the CNA's own assessment, by redhat; NVD's own analysis pending).
How do I remediate CVE-2026-50256?
A fix for CVE-2026-50256 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-50256 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-50256

Explore →

Is Your Infrastructure Affected by CVE-2026-50256?

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