In libssh2 before 1.9.0, kex_method_diffie_hellman_group_exchange_sha256_key_exchange in kex.c has an integer overflow that could lead to an
In libssh2 before 1.9.0, kex_method_diffie_hellman_group_exchange_sha256_key_exchange in kex.c has an integer overflow that could lead to an out-of-bounds read in the way packets are read from the server. A remote attacker who compromises a SSH server may be able to disclose sensitive information or cause a denial of service condition on the client system when a user connects to the server. This is related to an _libssh2_check_length mistake, and is different from the various issues fixed in 1.8.1, such as CVE-2019-3855.
- Published
- Jul 16, 2019
- Updated
- Jun 16, 2026
- EPSS
- 11.7% · 96th percentile
- CWE
- CWE-125
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Report tools
Action score
35
Monitor
Low priority for now.
- CVSS
- 32 / 40 · 8.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 3 / 30 · 11.7%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| libssh2 | libssh2 | cpe:2.3:a:libssh2:libssh2 |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| netapp | cloud backup | cpe:2.3:a:netapp:cloud_backup |
| netapp | e-series santricity os controller | cpe:2.3:a:netapp:e-series_santricity_os_controller |
| netapp | ontap select deploy administration utility | cpe:2.3:a:netapp:ontap_select_deploy_administration_utility |
| f5 | traffix systems signaling delivery controller | cpe:2.3:a:f5:traffix_systems_signaling_delivery_controller |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux8.0
- debian debian linux9.0
- f5 traffix systems signaling delivery controller5.0.0 and later · up to 5.1.0 inclusive
- fedoraproject fedora29
- fedoraproject fedora30
- libssh2 libssh2before 1.9.0
- netapp cloud backupall versions
- netapp e-series santricity os controller11.0.0 and later · up to 11.70.1 inclusive
- netapp ontap select deploy administration utilityall versions
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | libssh2 | before 1.9.0-r0 | 1.9.0-r0 |
| Debian:10 | libssh2 | before 1.8.0-2.1+deb10u1 | 1.8.0-2.1+deb10u1 |
| Debian:12 | libssh2 | before 1.9.0-1 | 1.9.0-1 |
| Debian:8 | libssh2 | before 1.4.3-4.1+deb8u4 | 1.4.3-4.1+deb8u4 |
| Debian:9 | libssh2 | before 1.7.0-1+deb9u2 | 1.7.0-1+deb9u2 |
Same product
libssh2: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-3861An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the way SSH packets with a padding length value greater than the packet38Monitor
- CVE-2019-3860An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the way SFTP packets with empty payloads are parsed.38Monitor
- CVE-2019-3858An out of bounds read flaw was discovered in libssh2 before 1.8.1 when a specially crafted SFTP packet is received from the server.38Monitor
- CVE-2019-3855An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way packets are read from 38Monitor
- CVE-2019-3862An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the way SSH_MSG_CHANNEL_REQUEST packets with an exit status message and38Monitor
- CVE-2019-3859An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the _libssh2_packet_require and _libssh2_packet_requirev functions.38Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| n/a n/a | 1.8.1 · description | Vendor (CNA) |
| Alpine:libssh2 | 1.9.0-r0 · Alpine:v3.10 | Package registry (OSV) |
| Debian:libssh2 | 1.9.0-1 · Debian:12 | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×2
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:1 | 2019-10-03 |
| Proof-of-concept repository on GitHub | stars:0 | 2019-10-03 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- First PoC+78 d
- TodaySep 30, 2026+2633 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-125 · Out-of-bounds ReadCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- packetstormsecurity.com/files/172834/libssh2-1.8.2-Out-Of-Bounds-Read.html
- github.com/libssh2/libssh2/compare/02ecf17...42d37aa
- github.com/libssh2/libssh2/pull/350
- libssh2.org/changes.html
- lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
- lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
- lists.debian.org/debian-lts-announce/2019/07/msg00024.html
- lists.debian.org/debian-lts-announce/2021/12/msg00013.html
- lists.debian.org/debian-lts-announce/2023/09/msg00006.html
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6LUNHPW64IGCASZ4JQ2J5KDXNZN53DWW/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M7IF3LNHOA75O4WZWIHJLIRMA5LJUED3/
- security.netapp.com/advisory/ntap-20190806-0002/
- support.f5.com/csp/article/K13322484
- support.f5.com/csp/article/K13322484?utm_source=f5support&%3Butm_medium=RSS
Vendor advisories and official records. Exploit/PoC links are deliberately left out.