CVE-2026-55200

HIGHNVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under NVD CVSS v3. EPSS exploit probability: 4.0%, top 10% 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
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 8.3Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

CVSS v3
8.3
EG Score
8.3HIGHmedium confidence
EG Risk
53
EG Risk 53/100

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
Severity83% × 45%
Exploitation40% × 40%
Automatability0% × 15%
EPSS PROB
0.8%
EPSS %ILE
56th
KEV
Not listed

Published

June 17, 2026

Last Modified

September 17, 2026

Advisory Details (5)

Auto-updated Jun 30, 2026
Patch available. Sources: github_commit, github_pr.
generic

exploitarium/libssh2-cve-2026-55200-poc at main · bikini/exploitarium · GitHub

https://web.archive.org/web/20260623211210/https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc
generic

libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-length-in-transport-c
github_pr

transport.c: Additional boundary checks for packet length

Fix merged in libssh2/libssh2 PR #2052 on 2026-06-12 — awaiting tagged release

https://github.com/libssh2/libssh2/pull/2052
github_commit

commit 97acf3dfda80 (libssh2/libssh2)

Fix landed in libssh2/libssh2 commit 97acf3dfda80 — awaiting tagged release

https://github.com/libssh2/libssh2/commit/97acf3dfda80c91c3a8c9f2372546301d4a1a7a8
generic

exploitarium/libssh2-cve-2026-55200-poc at main · bikini/exploitarium · GitHub

https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc

Vendor Advisories for CVE-2026-55200(3)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibssh2-1t64 (1.11.1-1ubuntu0.26.04.2) @ resolute2026-09-17ubuntu
redhatlibssh2-main-1.11.1-8.hum12026-06-25redhat

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 6 ecosystems)
Alpine:v3.24(2)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r3: fixed in 1.11.1-r3
—
rust—
  • every version up to 1.96.1-r0: fixed in 1.96.1-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r2: fixed in 1.11.1-r2
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r2: fixed in 1.11.1-r2
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r3: fixed in 1.11.1-r3
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libssh21.11.1-1
  • every version up to 1.11.1-1+deb13u1: fixed in 1.11.1-1+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libssh21.11.1-1, 1.11.1-2, 1.11.1-3
  • every version up to 1.11.1-4: fixed in 1.11.1-4
—

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

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCxd20111/CVE-2026-55200
    First seen Jun 29, 2026

    CVE-2026-55200 - Critical libssh2 Remote Code Execution Vulnerability

    Open source ↗
  • GitHub PoC0xBlackash/CVE-2026-55200
    First seen Jun 23, 2026

    CVE-2026-55200

    Open source ↗

Related CVEs(same product + same vendor + same CWE)

Same vendor

2 shown

redhat:RHSA-2026:29950 · ubuntu:USN-8486-1

Frequently asked(5)

What is CVE-2026-55200?
CVE-2026-55200 is a high vulnerability published on June 17, 2026. libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2transportread() that fails to enforce upper bounds on packetlength field. Remote attackers can send crafted SSH packets with excessively large packetlength values to corrupt heap memory and achieve…
When was CVE-2026-55200 disclosed?
CVE-2026-55200 was first published on June 17, 2026, with the most recent update on September 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55200 actively exploited?
CVE-2026-55200 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (56th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55200?
CVE-2026-55200 has a CVSS v3 base score of 8.3 (NVD).
How do I remediate CVE-2026-55200?
A fix for CVE-2026-55200 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55200 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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