CVE-2026-44988

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 4 sources updated this week
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0

A fix is available — apply it.

LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

May 27, 2026

Last Modified

June 1, 2026

Advisory Details (2)

Auto-updated May 28, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

LibVNCClient Tight Gradient decoding allows malicious server-triggered heap/stack OOB writes · Advisory · LibVNC/libvncserver · GitHub

https://github.com/LibVNC/libvncserver/security/advisories/GHSA-jcc5-8wj4-7c58
github_commit

commit 5b270544b852 (LibVNC/libvncserver)

Fix landed in LibVNC/libvncserver commit 5b270544b852 — awaiting tagged release

https://github.com/LibVNC/libvncserver/commit/5b270544b85233668b98161323297d418a8f5fd1

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibvncserver1 (0.9.15+dfsg-3ubuntu0.1) @ resolute2026-09-14ubuntu

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
libvncserver0.9.13+dfsg-2 ... 0.9.15+dfsg-6 (12 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libvncserver0.9.14+dfsg-1, 0.9.14+dfsg-1+deb12u10.9.14+dfsg-1+deb12u2—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libvncserver0.9.15+dfsg-1, 0.9.15+dfsg-1+deb13u10.9.15+dfsg-1+deb13u2—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libvncserver0.9.15+dfsg-1, 0.9.15+dfsg-2, 0.9.15+dfsg-3, 0.9.15+dfsg-40.9.15+dfsg-5—

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 9× in last 7d / 36× 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 190 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-44988?
CVE-2026-44988 is a high vulnerability published on May 27, 2026. LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server…
When was CVE-2026-44988 disclosed?
CVE-2026-44988 was first published in the National Vulnerability Database on May 27, 2026, with the most recent update on June 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44988 actively exploited?
CVE-2026-44988 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 84.5% of all scored CVEs.
What is the CVSS score of CVE-2026-44988?
CVE-2026-44988 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-44988?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44988, 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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