In JetBrains IntelliJ IDEA before 2026.3 code execution was possible in Safe Mode via UI Designer form file
- Exploited
- No known exploitation
- Fix
- Fixed in 2026.3
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 2026.3.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 9/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
JetBrains IntelliJ IDEA versions before 2026.3 are affected by a flaw that allows code execution while the IDE runs in Safe Mode, which is meant to block such behavior. An attacker with local access, without needing to log in, could exploit this if a user opens a malicious UI Designer form file, and the attack gives them full control over confidentiality, integrity, and availability.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
In JetBrains IntelliJ IDEA before 2026.3 code execution was possible in Safe Mode via UI Designer form file
cve.now Index
- Exploitation0/40No signal
- Exposure?/25Unknown. No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.8/10CVSS 7.8, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 64 if added to CISA KEV
- Would score about 59 if CISA's SSVC rates exploitation active
- Would score about 31 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 2026.3.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- JetBrains IntelliJ IDEA
fixed in 2026.3
Evidence 1
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123838
Is CVE-2026-123838 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-123838?
IntelliJ IDEA: before 2026.3.Source: cve.now feed data
How do I fix CVE-2026-123838?
Upgrade to a fixed version: 2026.3.Source: cve.now feed data