Multiple double free vulnerabilities in the (1) agent_sign_data function in agent.c, (2) channel_request function in channels.c, (3) ssh_use
Multiple double free vulnerabilities in the (1) agent_sign_data function in agent.c, (2) channel_request function in channels.c, (3) ssh_userauth_pubkey function in auth.c, (4) sftp_parse_attr_3 function in sftp.c, and (5) try_publickey_from_file function in keyfiles.c in libssh before 0.5.3 allow remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unspecified vectors.
- Published
- Nov 30, 2012
- Updated
- Jun 16, 2026
- EPSS
- 5.2% · 92th percentile
- CWE
- CWE-399
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
29
Monitor
Low priority for now.
- CVSS
- 27 / 40 · 6.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 2 / 30 · 5.2%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| libssh | libssh | cpe:2.3:a:libssh:libssh |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- libssh libsshup to 0.5.2 inclusive
- libssh libssh0.4.7
- libssh libssh0.4.8
- libssh libssh0.5.0
- libssh libssh0.5.1
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | libssh | before 0.5.3-1 | 0.5.3-1 |
| Debian:6.0 | libssh | before 0.4.5-3+squeeze1 | 0.4.5-3+squeeze1 |
| openSUSE:Tumbleweed | libssh | before 0.7.2-2.1 | 0.7.2-2.1 |
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 |
|---|---|---|
| debian:libssh | 0.5.3-1 · Debian:12 | Package registry (OSV) |
| opensuse:libssh | 0.7.2-2.1 · openSUSE:Tumbleweed | 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.
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
If successful
- Confidentiality
- P · data can be read
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- M
- Confidentiality impact
- P
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
CWE-399 · Resource Management ErrorsCVSS vector
AV:N/AC:M/Au:N/C:P/I:P/A:P
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.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
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
- lists.fedoraproject.org/pipermail/package-announce/2012-November/093313.html
- lists.fedoraproject.org/pipermail/package-announce/2012-November/093474.html
- lists.opensuse.org/opensuse-security-announce/2012-12/msg00002.html
- lists.opensuse.org/opensuse-updates/2012-12/msg00016.html
- lists.opensuse.org/opensuse-updates/2013-01/msg00021.html
- www.debian.org/security/2012/dsa-2577
- www.libssh.org/2012/11/20/libssh-0-5-3-security-release/
- www.mandriva.com/security/advisories?name=MDVSA-2012:175
- www.openwall.com/lists/oss-security/2012/11/20/3
- www.securityfocus.com/bid/56604
- www.ubuntu.com/usn/USN-1640-1
- bugzilla.redhat.com/show_bug.cgi?id=871612
- exchange.xforce.ibmcloud.com/vulnerabilities/80218
Vendor advisories and official records. Exploit/PoC links are deliberately left out.