Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.48% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2020
CVE-2015-5361High confidence
Junos: FTPS through SRX opens up wide range of data channel TCP ports
Unknown · Unknown
6.5MediumCVSS 3.1
Scheduled
Patch availableMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available01
What, why and how
Background For regular, unencrypted FTP traffic, the FTP ALG can inspect the unencrypted control channel and open related sessions for the FTP data channel. These related sessions (gates) are specific to source and destination IPs and ports of client and server. The design intent of the ftps-extensions option (which is disabled by default) is to provide similar functionality when the SRX secures the FTP/FTPS client. As the control channel is encrypted, the FTP ALG cannot inspect the port specific information and will open a wider TCP data channel (gate) from client IP to server IP on all destination TCP ports. In FTP/FTPS client environments to an enterprise network or the Internet, this is the desired behavior as it allows firewall policy to be written to FTP/FTPS servers on well-known control ports without using a policy with destination IP ANY and destination port ANY. Issue The ftps-extensions option is not intended or recommended where the SRX secures the FTPS server, as the wide data channel session (gate) will allow the FTPS client temporary access to all TCP ports on the FTPS server. The data session is associated to the control channel and will be closed when the control channel session closes. Depending on the configuration of the FTPS server, supporting load-balancer, and SRX inactivity-timeout values, the server/load-balancer and SRX may keep the control channel open for an extended period of time, allowing an FTPS client access for an equal duration. Note that the ftps-extensions option is not enabled by default.
What
Background For regular, unencrypted FTP traffic, the FTP ALG can inspect the unencrypted control channel and open related sessions for the FTP data channel. These related sessions (gates) are specific to source and destination IPs and ports of client and server. The design intent of the ftps-extensions option (which is disabled by default) is to provide similar functionality when the SRX secures the FTP/FTPS client. As the control channel is encrypted, the FTP ALG cannot inspect the port specific information and will open a wider TCP data channel (gate) from client IP to server IP on all destination TCP ports. In FTP/FTPS client environments to an enterprise network or the Internet, this is the desired behavior as it allows firewall policy to be written to FTP/FTPS servers on well-known control ports without using a policy with destination IP ANY and destination port ANY. Issue The ftps-extensions option is not intended or recommended where the SRX secures the FTPS server, as the wide data channel session (gate) will allow the FTPS client temporary access to all TCP ports on the FTPS server. The data session is associated to the control channel and will be closed when the control channel session closes. Depending on the configuration of the FTPS server, supporting load-balancer, and SRX inactivity-timeout values, the server/load-balancer and SRX may keep the control channel open for an extended period of time, allowing an FTPS client access for an equal duration. Note that the ftps-extensions option is not enabled by default.
Why
The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Background For regular, unencrypted FTP traffic, the FTP ALG can inspect the unencrypted control channel and open related sessions for the FTP data channel. These related sessions (gates) are specific to source and destination IPs and ports of client and server. The design intent of the ftps-extensions option (which is disabled by default) is to provide similar functionality when the SRX secures the FTP/FTPS client. As the control channel is encrypted, the FTP ALG cannot inspect the port specific information and will open a wider TCP data channel (gate) from client IP to server IP on all destination TCP ports. In FTP/FTPS client environments to an enterprise network or the Internet, this is the desired behavior as it allows firewall policy to be written to FTP/FTPS servers on well-known control ports without using a policy with destination IP ANY and destination port ANY. Issue The ftps-extensions option is not intended or recommended where the SRX secures the FTPS server, as the wide data channel session (gate) will allow the FTPS client temporary access to all TCP ports on the FTPS server. The data session is associated to the control channel and will be closed when the control channel session closes. Depending on the configuration of the FTPS server, supporting load-balancer, and SRX inactivity-timeout values, the server/load-balancer and SRX may keep the control channel open for an extended period of time, allowing an FTPS client access for an equal duration. Note that the ftps-extensions option is not enabled by default.
Why
The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Inadequate Encryption Strength → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-326 ↗
CWE-326: Inadequate Encryption Strength. The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- n/a
- Fixed
- The overall behavior of the FTP ALG with the ftps-extensions option is intended behavior and will not change. The key component to this advisory is increasing user awareness of the wide TCP data channel (gate) creation, allowing creation of any new sessions from client to server, and potential implications where the SRX protects the FTPS server and the server/load-balancer allows the control channel to remain open for an extended period.
- Investigation into the issue identified two issues applicable to environments where the SRX protects both FTPS clients and servers, as well as uses FTP and FTPS over the same TCP ports to different servers.
- Due to the recent changes of OpenSSL, the FTP ALG without the ftps-extensions option may block FTPS commands over the FTP control channel. This is client and server specific, and was observed with FTPS clients that use recent versions of OpenSSL. This may result in security administrators enabling the ftps-extensions option with the intent of allowing the commands to pass, but inadvertently allowing wide gate creation. This was observed in a configuration with simultaneous FTPS client/server use, with use of the same ports for FTP and FTPS traffic.
- The ftps-extension option is not supported when the SRX performs a destination NAT of the FTPS server, as the ALG cannot inspect the control channel to modify the server’s IP address signaled to the client. In an environment of simultaneous FTP and FTPS server use with the ftps-extensions option enabled, the gate is created but is generally unusable by the FTPS client. However, an FTPS client with knowledge of the server’s real IP address, its NAT’d IP address, and routing reachability to the server’s real IP address may be able to use the wide gate to reach the FTPS server.
- The software releases listed below resolves these issues as follows:
- The FTP ALG without the ftps-extensions option will allow FTPS related commands to pass over the FTP control channel. As the ftps-extension
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 28 Feb 2020 · Last source change 16 Sept 2024, 16:39 UTC · CWE-326 · Inadequate Encryption Strength
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2015-5317
Product sourceUnavailable
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment
Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.