TI-2026-85877 Aliases CVE-2026-123336 GHSA-gv5f-529c-m3rx

Attachment size limit bypass in JetBrains YouTrack AI assistant

LOW 17CWE-770Published 2026-11-06 · Updated 2026-11-06

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: High
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · Low
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-770.

Summary

JetBrains YouTrack before 2026.2.19728 does not enforce its attachment size limit when a thread is converted through the AI assistant. A remote attacker with low privileges can exceed the limit, which causes resource exhaustion (CWE-770). The CVSS vector rates the impact as low availability only.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

In JetBrains YouTrack before 2026.2.19728 the attachment size limit could be bypassed via AI assistant thread conversion

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00763 55th percentileScored 2026-11-07

Fix Fixed YouTrack (JetBrains): 2026.2.19728

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
JetBrains	YouTrack	before 2026.2.19728	2026.2.19728	Patch available	CNA

YouTrack VendorJetBrains Affected before 2026.2.19728 Fixed in 2026.2.19728 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:jetbrains:youtrack::::::::	—	—	JetBrains

cpe:2.3:a:jetbrains:youtrack:*:*:*:*:*:*:*:* Versions — — ·JetBrains

Remediation

Update JetBrains YouTrack to version 2026.2.19728 or later.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Fix · CNA YouTrack (JetBrains) Fixed in 2026.2.19728

Timeline

2026-11-06 Threatist record created from CVE-2026-123336
2026-11-06 Alias added: GHSA-gv5f-529c-m3rx
2026-11-06 CISA SSVC decision points changed

References

Other 1

https://www.jetbrains.com/privacy-security/issues-fixed/

TI-2026-45031 Deserialization of untrusted data in JetBrains TeamCity KEVCVSS 3.1CRITICAL 9.8
TI-2024-18053 In JetBrains TeamCity before 2023.11.4 authentication bypass allowing to perform admin actions was possible KEVCVSS 3.1CRITICAL 9.8
TI-2023-22884 In JetBrains TeamCity before 2023.05.4 authentication bypass leading to RCE on TeamCity Server was possible KEVCVSS 3.1CRITICAL 9.8
TI-2024-18054 In JetBrains TeamCity before 2023.11.4 path traversal allowing to perform limited admin actions was possible KEVCVSS 3.1HIGH 7.3
TI-2024-15905 In JetBrains TeamCity before 2023.11.3 authentication bypass leading to RCE was possible CVSS 3.1CRITICAL 9.8
TI-2024-24589 Insufficiently protected credentials in JetBrains IntelliJ IDEA CVSS 3.1CRITICAL 9.3

See all 787 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences