CVE-2025-15661

MEDIUMNVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-06-18. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

A fix is available — apply it.

libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.

CVSS v3
6.5
EG Score
6.5(high)
EPSS
18.3%
KEV
Not listed

Published

June 18, 2026

Last Modified

June 26, 2026

Advisory Details (4)

Auto-updated Jun 18, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c
github_pr

Update sftp_symlink to avoid out of bounds read #1705

Fix merged in libssh2/libssh2 PR #1717 on 2025-10-10 — awaiting tagged release

https://github.com/libssh2/libssh2/pull/1717
github_pr

sftp: fix OOB read on READLINK/REALPATH name parsing

Upstream fix in progress (PR #1705 · libssh2/libssh2, state=closed)

https://github.com/libssh2/libssh2/pull/1705
github_commit

commit 2dae3024897e (libssh2/libssh2)

Fix landed in libssh2/libssh2 commit 2dae3024897e — awaiting tagged release

https://github.com/libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d

Vendor Advisories for CVE-2025-15661(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 / EcosystemFixed in / PatchReleasedSource
ubuntulibssh2-1t64 (1.11.1-1ubuntu0.26.04.2) @ resolute2026-07-06ubuntu
redhatlibssh2-main-1.11.1-9.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.

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 28× in last 7d / 66× 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.

  1. 2026-07-06 21:34 UTCEG score recompute
  2. 2026-07-06 21:34 UTCVendor advisory
  3. 2026-07-06 21:34 UTCGHSA enrichment
  4. 2026-07-06 16:26 UTCEPSS rescore
  5. 2026-07-06 02:22 UTCEPSS rescore
  6. 2026-07-06 02:22 UTCEPSS rescore
  7. 2026-07-05 20:36 UTCEG score recompute
  8. 2026-07-05 20:36 UTCVendor advisory
  9. 2026-07-05 20:36 UTCGHSA enrichment
  10. 2026-07-05 02:30 UTCEPSS rescore
  11. 2026-07-04 20:39 UTCEG score recompute
  12. 2026-07-04 20:39 UTCVendor advisory
  13. 2026-07-04 20:39 UTCGHSA enrichment
  14. 2026-07-04 06:30 UTCEPSS rescore
  15. 2026-07-03 20:41 UTCEG score recompute
  16. 2026-07-03 20:41 UTCVendor advisory
  17. 2026-07-03 20:41 UTCGHSA enrichment
  18. 2026-07-02 20:43 UTCEG score recompute
  19. 2026-07-02 20:43 UTCVendor advisory
  20. 2026-07-02 20:43 UTCGHSA enrichment
  21. 2026-07-01 20:45 UTCEG score recompute
  22. 2026-07-01 20:45 UTCVendor advisory
  23. 2026-07-01 20:45 UTCGHSA enrichment
  24. 2026-07-01 15:06 UTCEPSS rescore
  25. 2026-06-30 23:21 UTCEPSS rescore
Show 41 more
  1. 2026-06-30 20:49 UTCEG score recompute
  2. 2026-06-30 20:49 UTCVendor advisory
  3. 2026-06-30 20:49 UTCGHSA enrichment
  4. 2026-06-29 20:52 UTCEG score recompute
  5. 2026-06-29 20:52 UTCVendor advisory
  6. 2026-06-29 20:52 UTCGHSA enrichment
  7. 2026-06-29 14:06 UTCEPSS rescore
  8. 2026-06-28 20:56 UTCEG score recompute
  9. 2026-06-28 20:56 UTCVendor advisory
  10. 2026-06-28 20:56 UTCGHSA enrichment
  11. 2026-06-28 14:07 UTCEPSS rescore
  12. 2026-06-28 14:07 UTCEPSS rescore
  13. 2026-06-28 04:55 UTCEPSS rescore
  14. 2026-06-27 20:59 UTCEG score recompute
  15. 2026-06-27 20:59 UTCVendor advisory
  16. 2026-06-27 20:59 UTCGHSA enrichment
  17. 2026-06-27 03:08 UTCEPSS rescore
  18. 2026-06-27 03:08 UTCEPSS rescore
  19. 2026-06-26 21:03 UTCEG score recompute
  20. 2026-06-26 21:02 UTCGHSA enrichment
  21. 2026-06-25 21:06 UTCEG score recompute
  22. 2026-06-25 21:06 UTCGHSA enrichment
  23. 2026-06-25 13:49 UTCEPSS rescore
  24. 2026-06-25 13:49 UTCEPSS rescore
  25. 2026-06-24 21:06 UTCEG score recompute
  26. 2026-06-24 21:06 UTCGHSA enrichment
  27. 2026-06-24 14:04 UTCEPSS rescore
  28. 2026-06-24 14:04 UTCEPSS rescore
  29. 2026-06-23 21:32 UTCEPSS rescore
  30. 2026-06-23 21:10 UTCEG score recompute
  31. 2026-06-23 21:09 UTCGHSA enrichment
  32. 2026-06-22 21:13 UTCEG score recompute
  33. 2026-06-22 21:13 UTCGHSA enrichment
  34. 2026-06-21 21:14 UTCEG score recompute
  35. 2026-06-21 21:14 UTCGHSA enrichment
  36. 2026-06-20 21:17 UTCEG score recompute
  37. 2026-06-20 21:17 UTCGHSA enrichment
  38. 2026-06-19 21:20 UTCEG score recompute
  39. 2026-06-19 21:20 UTCGHSA enrichment
  40. 2026-06-18 21:23 UTCEG score recompute
  41. 2026-06-18 21:23 UTCNVD updatefirst tracked

Frequently asked(5)

What is CVE-2025-15661?
CVE-2025-15661 is a medium vulnerability published on June 18, 2026. libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftpsymlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSHFXPNAME response.…
When was CVE-2025-15661 disclosed?
CVE-2025-15661 was first published in the National Vulnerability Database on June 18, 2026, with the most recent update on June 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-15661 actively exploited?
CVE-2025-15661 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 18.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-15661?
CVE-2025-15661 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2025-15661?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-15661, 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

Explore the affected products and dependency analysis for CVE-2025-15661

Explore →

Is Your Infrastructure Affected by CVE-2025-15661?

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

Start Free Scan →Browse All CVEs