CVE-2026-31951: LibreChat is a ChatGPT clone with additional features

Routine

MEDIUM 6.8UPGRADE

CVE-2026-31951 is a medium-severity flaw (CVSS 6.8) affecting librechat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP (Model Context Protocol) servers can include arbitrary HTTP headers that undergo credential placeholder substitution. An attacker can create a malicious MCP server with headers containing `{{LIBRECHAT_OPENID_ACCESS_TOKEN}}` (and others), causing victims who call tools on that server to have their OAuth tokens exfiltrated. Version 0.8.3

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.8 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 83%)
CISA exploited list	No
Weakness	CWE-200
Published	2026-03-27
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: librechat

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-27 20:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

librechat librechat UPGRADE

Affected: >= 0.8.2 and < 0.8.3 · 0.8.3 rc1

Fixed in: 0.8.3

Safe to downgrade to: a release before 0.8.2

1. Check installed version

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

2. UPGRADE to 0.8.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade librechat

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade librechat

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.8.2 (Debian / Ubuntu)

apt-cache madison librechat sudo apt install librechat=<VERSION_BEFORE_0.8.2> sudo apt-mark hold librechat

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list librechat sudo dnf downgrade librechat-<VERSION_BEFORE_0.8.2> sudo dnf versionlock add librechat

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-2026-31951?

librechat: upgrade to 0.8.3. Exact commands for each OS are on this page.

Is CVE-2026-31951 being exploited?

CVE-2026-31951 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-2026-31951 affect?

CVE-2026-31951 affects librechat. Severity is medium (CVSS 6.8). LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP (Model Context Protocol) servers can include arbitrary HTTP headers that undergo credential placeholder substitution. An attack

How urgent is CVE-2026-31951?

Priority 33/100. Public exploit reference

Software pages

OpenAI ChatGPT vulnerabilities

Related CVEs

CVE-2026-31943 HIGH 8.5 UPGRADE LibreChat is a ChatGPT clone with additional features
CVE-2026-31945 HIGH 7.7 DOWNGRADE LibreChat is a ChatGPT clone with additional features
CVE-2026-31950 MEDIUM 5.3 DOWNGRADE LibreChat is a ChatGPT clone with additional features
CVE-2026-54033 HIGH 7.7 UPGRADE LibreChat is an enhanced ChatGPT clone that supports multiple AI providers
CVE-2026-54037 MEDIUM 6.5 UPGRADE LibreChat is an enhanced ChatGPT clone that supports multiple AI providers

References

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