CVE-2026-4964: A security vulnerability has been detected in letta-ai letta 0.16.4

Routine

MEDIUM 6.3DOWNGRADE

CVE-2026-4964 is a medium-severity flaw (CVSS 6.3) affecting letta. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 th

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 73%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-03-27
Last modified	2026-06-17

Publisher (CNA): VulDB · Vendor: letta

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-27 17:16 UTCPublished CVE record published
2026-06-17 10:57 UTCUpdated Record last modified

letta letta DOWNGRADE

Affected: 0.16.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.16.4

1. Check installed version

apt-cache policy letta || rpm -q letta || letta --version

2. No fixed release: DOWNGRADE to a release before 0.16.4 (Debian / Ubuntu)

apt-cache madison letta sudo apt install letta=<VERSION_BEFORE_0.16.4> sudo apt-mark hold letta

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list letta sudo dnf downgrade letta-<VERSION_BEFORE_0.16.4> sudo dnf versionlock add letta

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-4964?

letta: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-4964 being exploited?

CVE-2026-4964 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-4964 affect?

CVE-2026-4964 affects letta. Severity is medium (CVSS 6.3). 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

How urgent is CVE-2026-4964?

Priority 34/100. Public exploit reference

Related CVEs

CVE-2026-4965 HIGH 7.3 DOWNGRADE A vulnerability was detected in letta-ai letta 0.16.4

References

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