Security readout for executives and security teams
Plain-English summary
CVE-2026-21914 can make affected Juniper SRX firewalls temporarily stop forwarding traffic. A malformed GTP Modify Bearer Request can trigger an FPC crash and restart, causing a complete traffic outage until automatic recovery. This is a high-urgency availability issue for SRX deployments handling or inspecting GTP traffic.
Executive priority
Prioritize remediation for SRX firewalls supporting mobile, carrier, roaming, or GTP-aware environments. The business risk is service interruption rather than data theft. Patch scheduling should consider that a single malformed network message may trigger device traffic outage until recovery on affected systems.
Technical view
The flaw is an improper locking issue in the Junos OS GTP plugin on SRX Series. A malformed GTP Modify Bearer Request causes a lock to remain unreleased, blocking other threads and leading to a watchdog timeout, FPC crash, and restart. It is network-accessible, unauthenticated, and rated CVSS 4.0 score 8.7.
Likely exposure
Exposure is most likely where SRX Series devices run affected Junos OS releases and have GTP processing reachable from untrusted or semi-trusted networks. The source bundle lists only SRX Series running Junos OS as affected; do not assume other Juniper products are impacted without vendor confirmation.
Exploitation context
The CVE is not listed as KEV in the provided data, and no cited source states active exploitation. The attack requires network delivery of a malformed GTP Modify Bearer Request to an affected SRX device’s GTP plugin path. Successful exploitation affects availability, not confidentiality or integrity, based on the provided CVSS vector.
Researcher notes
Evidence is limited to the CVE record and Juniper advisory references in the source bundle. The vulnerability is CWE-667 improper locking and impacts availability through FPC crash/restart. No public exploit status, workaround details, or broader product impact is provided in the supplied sources.
Mitigation direction
- Upgrade affected SRX devices to the fixed Junos OS releases named by Juniper.
- Use 22.4R3-S8 or later for 22.4 trains.
- Use 23.2R2-S5 or later for 23.2 trains.
- Use 23.4R2-S6 or later for 23.4 trains.
- Use 24.2R2-S3 or later for 24.2 trains.
- Use 24.4R2-S2 or later for 24.4 trains.
Validation and detection
- Inventory SRX Series devices and record Junos OS versions.
- Check whether GTP functionality is enabled or exposed on SRX traffic paths.
- Compare versions against Juniper’s affected and fixed release list.
- Review logs for FPC crash, watchdog timeout, or unexpected restart events.
- Confirm remediation status against Juniper advisory JSA106015.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-667: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-21914 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
8.7HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M
Source materials
- CVE List V5 sourceCVE List V5
- https://supportportal.juniper.net/JSA106015CVE reference · vendor-advisory
- https://kb.juniper.net/JSA106015CVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Locking
Improper Locking represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.