Libssh: libssh: information disclosure via short gssapi curve25519 public key
A flaw was found in libssh. During server-side GSSAPI key exchange, a client-supplied Curve25519 public key shorter than the expected length is copied without proper length validation, leading to an out-of-bounds heap read. This could allow a remote unauthenticated attacker to disclose small amounts of server memory.
- Published
- Jul 21, 2026
- Updated
- Sep 22, 2026
- EPSS
- 0.5% · 40th percentile
- CWE
- CWE-125
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Report tools
Action score
21
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 5.3
- CNA · redhat
- 3.7
- 1.6 point gap
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; 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 helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| libssh | libssh | cpe:2.3:a:libssh:libssh |
| redhat | hardened images | cpe:2.3:a:redhat:hardened_images |
| redhat | enterprise linux | cpe:2.3:o:redhat:enterprise_linux |
| redhat | enterprise linux for els | cpe:2.3:o:redhat:enterprise_linux_for_els |
| redhat | enterprise linux for eus | cpe:2.3:o:redhat:enterprise_linux_for_eus |
| redhat | enterprise linux for ibm z systems | cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems |
| redhat | enterprise linux for ibm z systems els | cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_els |
| redhat | enterprise linux for ibm z systems eus | cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus |
| redhat | enterprise linux for power little endian | cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian |
| redhat | enterprise linux for power little endian els | cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_els |
| redhat | enterprise linux for power little endian eus | cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- libssh libssh0.12.0
- redhat enterprise linux10.0
- redhat enterprise linux10.2
- redhat enterprise linux for els10.2
- redhat enterprise linux for eus10.2
- redhat enterprise linux for ibm z systems10.0
- redhat enterprise linux for ibm z systems10.2
- redhat enterprise linux for ibm z systems els10.2
- redhat enterprise linux for ibm z systems eus10.2
- redhat enterprise linux for power little endian10.0
- redhat enterprise linux for power little endian10.2
- redhat enterprise linux for power little endian els10.2
- redhat enterprise linux for power little endian eus10.2
- redhat hardened imagesall versions
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
Red Hat Red Hat Enterprise Linux 10
- 0:0.12.0-3.el10_2 and laternot affected · rpm
Red Hat Red Hat Enterprise Linux 8
- all versionsunknown
Red Hat Red Hat Enterprise Linux 9
- all versionsunknown
Red Hat Red Hat Hardened Images
- 0.12.1-4.hum1 and laternot affected · rpm
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | libssh | before 0.12.0-3.el10_2 | 0.12.0-3.el10_2 |
| AlmaLinux:10 | libssh-config | before 0.12.0-3.el10_2 | 0.12.0-3.el10_2 |
| AlmaLinux:10 | libssh-devel | before 0.12.0-3.el10_2 | 0.12.0-3.el10_2 |
| Debian:14 | libssh | before 0.12.1-1 | 0.12.1-1 |
| Red Hat:enterprise_linux:10.2 | libssh | before 0:0.12.0-3.el10_2 | 0:0.12.0-3.el10_2 |
| Red Hat:enterprise_linux:10.2 | libssh-config | before 0:0.12.0-3.el10_2 | 0:0.12.0-3.el10_2 |
| Red Hat:enterprise_linux:10.2 | libssh-debuginfo | before 0:0.12.0-3.el10_2 | 0:0.12.0-3.el10_2 |
| Red Hat:enterprise_linux:10.2 | libssh-debugsource | before 0:0.12.0-3.el10_2 | 0:0.12.0-3.el10_2 |
| Red Hat:enterprise_linux:10.2 | libssh-devel | before 0:0.12.0-3.el10_2 | 0:0.12.0-3.el10_2 |
| Red Hat:hummingbird:1 | libssh | before 0:0.12.1-4.hum1 | 0:0.12.1-4.hum1 |
| Red Hat:hummingbird:1 | libssh-config | before 0:0.12.1-4.hum1 | 0:0.12.1-4.hum1 |
| Rocky Linux:10 | libssh | before 0:0.12.0-3.el10_2 | 0:0.12.0-3.el10_2 |
Same product
libssh: all recordsOther highest-scoring records for the same primary product.
- CVE-2018-10933A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4.64This week
- CVE-2019-14889A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.36Monitor
- CVE-2026-59851Libssh: libssh: authentication bypass via missing gssapi principal check35Monitor
- CVE-2025-5372Libssh: incorrect return code handling in ssh_kdf() in libssh35Monitor
- CVE-2012-4562Multiple integer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (infinite loop or crash) and possibly 34Monitor
- CVE-2026-0966Libssh: libssh: denial of service via zero-length input in ssh_get_hexa()32Monitor
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 |
|---|---|---|
| almalinux:libssh | 0.12.0-3.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:libssh-config | 0.12.0-3.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:libssh-devel | 0.12.0-3.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| debian:libssh | 0.12.1-1 · Debian:14 | Package registry (OSV) |
| red hat:libssh | 0:0.12.1-4.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:libssh-config | 0:0.12.1-4.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:libssh-debuginfo | 0:0.12.0-3.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:libssh-debugsource | 0:0.12.0-3.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:libssh-devel | 0:0.12.0-3.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| rocky linux:libssh | 0:0.12.0-3.el10_2 · Rocky Linux:10 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
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.
No dated events beyond publication.
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.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2025-5318392 days apartLibssh: out-of-bounds read in sftp_handle()22Monitor
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).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-0601 · Jul 22, 2026(libssh Güvenlik Zafiyeti)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-125 · Out-of-bounds ReadCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- access.redhat.com/errata/RHSA-2026:42922
- access.redhat.com/errata/RHSA-2026:55855
- access.redhat.com/security/cve/CVE-2026-59842
- bugzilla.redhat.com/show_bug.cgi?id=2498168
Vendor advisories and official records. Exploit/PoC links are deliberately left out.