Libssh: write beyond bounds in binary to base64 conversion functions
Priority LOW 20CWE-787Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to ssh_get_fingerprint_hash() function. In such cases the bin_to_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's possible that the program perform out of bounds write leading to a heap corruption. This issue affects only 32-bits builds of libssh.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00203 10th percentileScored 2026-11-07
Fix Fixed libssh: 0.11.2Red Hat: 1 advisory
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | libssh | before 0.11.2 | 0.11.2 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 0.10.4-18.el9 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 0.10.4-18.el9 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 10 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 6 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 7 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | — | Not affected | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | Not affected | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | Not affected | CNA |
- libssh Vendor— Affected before 0.11.2 Fixed in 0.11.2 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 0.10.4-18.el9 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 0.10.4-18.el9 Patch available CNA
- Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
CPE names CNA · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:/a:redhat:enterprise_linux:9::appstream | 9 | — | Red Hat |
| cpe:/o:redhat:enterprise_linux:9::baseos | 9 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:10 | 10 | — | Red Hat |
| cpe:/o:redhat:rhel_els:6 | 6 | — | Red Hat |
| cpe:/o:redhat:rhel_els:7 | 7 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:8 | 8 | — | Red Hat |
| cpe:/a:redhat:openshift:4 | 4 | — | Red Hat |
- cpe:/a:redhat:enterprise_linux:9::appstream Versions 9 — ·Red Hat
- cpe:/o:redhat:enterprise_linux:9::baseos Versions 9 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:10 Versions 10 — ·Red Hat
- cpe:/o:redhat:rhel_els:6 Versions 6 — ·Red Hat
- cpe:/o:redhat:rhel_els:7 Versions 7 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:8 Versions 8 — ·Red Hat
- cpe:/a:redhat:openshift:4 Versions 4 — ·Red Hat
Remediation
- Fix · CNA libssh Fixed in 0.11.2
Red Hat 1 advisory
- RHSA-2026:18683 Released 2026-05-19 · Red Hat rating Moderatelibssh security update
- Red Hat Enterprise Linux AppStream (v. 9) libssh-devel-0.10.4-18.el9
- Red Hat Enterprise Linux BaseOS (v. 9) libssh-0.10.4-18.el9, libssh-config-0.10.4-18.el9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:18683 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:18683 |
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2025-4877
- 2026-10-03 Alias added: GHSA-pwrf-jm93-99r3
References
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Sources
- CVE-2025-4877 · CVE Program
- CVE-2025-4877 · NVD
- FIRST EPSS
- GHSA-pwrf-jm93-99r3 · GitHub Advisory Database · CC BY 4.0
- CVE-2025-4877 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences