EUVD-2026-27390
GHSA-wmvv-fhm6-w34x
Severity by source
CVSS:4.0/AV:A/AC:H/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:4.0/AV:A/AC:H/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
2DescriptionCVE.org
A flaw has been found in chatchat-space Langchain-Chatchat up to 0.3.1.3. This issue affects the function PIL.Image.tobytes of the file libs/chatchat-server/chatchat/webui_pages/dialogue/dialogue.py of the component Vision Chat Paste Image Handler. This manipulation of the argument paste_image.image_data causes use of weak hash. The attacker needs to be present on the local network. The attack is considered to have high complexity. The exploitability is assessed as difficult. The exploit has been published and may be used. The project was informed of the problem early through an issue report but has not responded yet.
AnalysisAI
Weak hash function in the Vision Chat Paste Image Handler of Langchain-Chatchat up to 0.3.1.3 allows local network attackers with low privileges to cause information disclosure via hash collision attacks on image data processed through PIL.Image.tobytes. The vulnerability requires high attack complexity and local network presence, resulting in minimal direct impact (CVSS 1.2); however, publicly available exploit code exists and the vendor has not responded to disclosure.
Technical ContextAI
The vulnerability resides in the Vision Chat Paste Image Handler component (libs/chatchat-server/chatchat/webui_pages/dialogue/dialogue.py), specifically in the PIL.Image.tobytes function call used to process paste_image.image_data. The root cause is CWE-328 (Use of Insufficiently Random Values), manifesting as use of weak cryptographic hash functions for image data integrity. An attacker on the local network can manipulate the paste_image.image_data argument to trigger hash collisions, allowing crafted image payloads to be processed as legitimate data. The exploitation requires low-level privilege access and high technical complexity, suggesting the hash function is used in a non-critical but information-disclosure context, such as image deduplication or caching mechanisms.
RemediationAI
No vendor-released patch identified at time of analysis; the project maintainers have not responded to early disclosure. Until a patched version is available, implement network segmentation to restrict access to the Langchain-Chatchat deployment to trusted users only-specifically, disable local network image paste functionality (Vision Chat Paste Image Handler) if not actively required. Alternatively, replace the weak hash function used in PIL.Image.tobytes processing with a cryptographically secure hash (SHA-256 or better) in the dialogue.py component; this requires code modification and testing before production deployment. Monitor https://github.com/chatchat-space/Langchain-Chatchat/issues/5462 and official project releases for vendor security patches. The trade-off of disabling image paste is usability reduction; code-level mitigation requires internal development resources but preserves feature availability.
More in Langchain Chatchat
View allMissing authentication in Langchain-Chatchat up to version 0.3.1.3 allows unauthenticated local network attackers to acc
Insufficiently random file ID generation in Langchain-Chatchat up to version 0.3.1.3 allows authenticated local network
Time-of-check time-of-use (TOCTOU) vulnerability in Langchain-Chatchat up to 0.3.1.3 allows authenticated local network
Same weakness CWE-328 – Use of Weak Hash
View allSame technique Information Disclosure
View allShare
External POC / Exploit Code
Leaving vuln.today