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Fencer Intel
medium 6.3

CVE-2026-4964 json

letta-ai letta File URL message_helper.py _convert_message_create_to_message server-side request forgery

published 7mo ago modified 4mo ago also EUVD-2026-16727

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

A security vulnerability has been detected in letta-ai letta 0.16.4. This vulnerability affects the function _convert_message_create_to_message of the file letta/helpers/message_helper.py of the component File URL Handler. Such manipulation of the argument ImageContent leads to server-side request forgery. It is possible to launch the attack remotely. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
7mo ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • gist.github.com https://gist.github.com/YLChen-007/fde4d5ed6ac4aa876f73f8954c6214da referenced PoC, tagged "exploit" by a source, unverified
  • vuldb.com https://vuldb.com/?submit.777645 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
CNA 3.0 6.3 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
CNA 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:ND/RC:UR
CNA 4.0 2.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/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
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CNA 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P

Affected products

  • letta-ai letta

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.