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CVE-2023-2283· NVD / CVE Program· CNA redhat

A vulnerability was found in libssh, where the authentication check of the connecting client can be bypassed in the`pki_verify_data_signatur

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1% (FIRST EPSS); higher than 63.9% of all records.
  • 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.
  • Fixed version: libssh (AlmaLinux:8) 0.9.6-10.el8_8; libssh-config (AlmaLinux:8) 0.9.6-10.el8_8; libssh-devel (AlmaLinux:8) 0.9.6-10.el8_8.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to libssh (AlmaLinux:8) 0.9.6-10.el8_8; libssh-config (AlmaLinux:8) 0.9.6-10.el8_8; libssh-devel (AlmaLinux:8) 0.9.6-10.el8_8 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A vulnerability was found in libssh, where the authentication check of the connecting client can be bypassed in the`pki_verify_data_signature` function in memory allocation problems. This issue may happen if there is insufficient memory or the memory usage is limited. The problem is caused by the return value `rc,` which is initialized to SSH_ERROR and later rewritten to save the return value of the function call `pki_key_check_hash_compatible.` The value of the variable is not changed between this point and the cryptographic verification. Therefore any error between them calls `goto error` returning SSH_OK.

MediumCVSS 6.5 · v3.1—No exploit Fix available
Published
May 26, 2023
Updated
Jun 17, 2026
EPSS
1.0% · 63th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.0%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
libsshlibssh
fedoraprojectfedora
redhatenterprise linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fedoraproject fedora37
  • libssh libssh0.9.1 and later · up to 0.9.6 inclusive
  • libssh libssh0.10.0 and later · up to 0.10.4 inclusive
  • redhat enterprise linux8.0
  • redhat enterprise linux9.0

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.

  • n/a libssh

    • libssh-2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8libsshbefore 0.9.6-10.el8_80.9.6-10.el8_8
AlmaLinux:8libssh-configbefore 0.9.6-10.el8_80.9.6-10.el8_8
AlmaLinux:8libssh-develbefore 0.9.6-10.el8_80.9.6-10.el8_8
AlmaLinux:9libsshbefore 0.10.4-11.el90.10.4-11.el9
AlmaLinux:9libssh-configbefore 0.10.4-11.el90.10.4-11.el9
AlmaLinux:9libssh-develbefore 0.10.4-11.el90.10.4-11.el9
Debian:11libsshbefore 0.9.7-0+deb11u10.9.7-0+deb11u1
Debian:12libsshbefore 0.10.5-10.10.5-1
openSUSE:Tumbleweedlibsshbefore 0.10.5-1.10.10.5-1.1
Red Hat:enterprise_linux:8::appstreamlibssh-debuginfobefore 0:0.9.6-10.el8_80:0.9.6-10.el8_8
Red Hat:enterprise_linux:8::appstreamlibssh-debugsourcebefore 0:0.9.6-10.el8_80:0.9.6-10.el8_8
Red Hat:enterprise_linux:8::appstreamlibssh-develbefore 0:0.9.6-10.el8_80:0.9.6-10.el8_8
Red Hat:enterprise_linux:8::baseoslibsshbefore 0:0.9.6-10.el8_80:0.9.6-10.el8_8
Red Hat:enterprise_linux:8::baseoslibssh-configbefore 0:0.9.6-10.el8_80:0.9.6-10.el8_8
Red Hat:enterprise_linux:9::appstreamlibssh-debuginfobefore 0:0.10.4-11.el90:0.10.4-11.el9
Red Hat:enterprise_linux:9::appstreamlibssh-debugsourcebefore 0:0.10.4-11.el90:0.10.4-11.el9
Red Hat:enterprise_linux:9::appstreamlibssh-develbefore 0:0.10.4-11.el90:0.10.4-11.el9
Red Hat:enterprise_linux:9::baseoslibsshbefore 0:0.10.4-11.el90:0.10.4-11.el9
Red Hat:enterprise_linux:9::baseoslibssh-configbefore 0:0.10.4-11.el90:0.10.4-11.el9
Red Hat:rhel_eus:8.6::appstreamlibssh-debuginfobefore 0:0.9.6-4.el8_60:0.9.6-4.el8_6
Red Hat:rhel_eus:8.6::appstreamlibssh-debugsourcebefore 0:0.9.6-4.el8_60:0.9.6-4.el8_6
Red Hat:rhel_eus:8.6::appstreamlibssh-develbefore 0:0.9.6-4.el8_60:0.9.6-4.el8_6
Red Hat:rhel_eus:8.6::baseoslibsshbefore 0:0.9.6-4.el8_60:0.9.6-4.el8_6
Red Hat:rhel_eus:8.6::baseoslibssh-configbefore 0:0.9.6-4.el8_60:0.9.6-4.el8_6

+5

Same product

libssh: all records

Other 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 check
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-3634Aug 31, 2021 · A flaw has been found in libssh in versions prior to 0.9.6.
    27Monitor
  • ← EarlierCVE-2023-1667May 26, 2023 · A NULL pointer dereference was found In libssh during re-keying with algorithm guessing.
    26Monitor
  • Later →CVE-2023-3603Jul 21, 2023 · Processing sftp server read may cause null dereference
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:libssh0.9.6-10.el8_8 · AlmaLinux:8Package registry (OSV)
almalinux:libssh-config0.9.6-10.el8_8 · AlmaLinux:8Package registry (OSV)
almalinux:libssh-devel0.9.6-10.el8_8 · AlmaLinux:8Package registry (OSV)
debian:libssh0.10.5-1 · Debian:12Package registry (OSV)
opensuse:libssh0.9.8-150400.3.3.1 · openSUSE:Leap Micro 5.3Package registry (OSV)
red hat:libssh0:0.9.6-10.el8_8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libssh-config0:0.9.6-10.el8_8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libssh-debuginfo0:0.9.6-10.el8_8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libssh-debugsource0:0.9.6-10.el8_8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libssh-devel0:0.9.6-10.el8_8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
rocky linux:libssh0:0.9.6-10.el8_8 · Rocky Linux:8Package registry (OSV)
suse:libssh0.9.8-150400.3.3.1 · SUSE:Linux Enterprise Micro 5.3Package 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.

EPSS, last 120 days

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 researchers

Finders, 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

nvd-primary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
app.use("/admin", requireSession, adminRouter);
// Route added later skips the middlewareapp.post("/admin-api/config", updateConfig);

Fixed

ts
const admin = express.Router();admin.use(requireSession, requireRole("admin"));
admin.post("/config", updateConfig);app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records