CVE-2026-40217: LiteLLM through 2026-04-08 allows remote attackers to execute arbitrary code via bytecode rewriting at the /gu

Q: How do I fix CVE-2026-40217?

litellm: upgrade to newer than 2026-04-08. Exact commands for each OS are on this page.

Q: Is CVE-2026-40217 being exploited?

CVE-2026-40217 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-40217 affect?

CVE-2026-40217 affects litellm. Severity is high (CVSS 8.8). LiteLLM through 2026-04-08 allows remote attackers to execute arbitrary code via bytecode rewriting at the /guardrails/test_custom_code URI.

Q: How urgent is CVE-2026-40217?

Priority 60/100. High severity; EPSS top 3%: very likely to be exploited; Public exploit reference

This week

HIGH 8.8UPGRADE

CVE-2026-40217 is a high-severity flaw (CVSS 8.8) affecting litellm. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LiteLLM through 2026-04-08 allows remote attackers to execute arbitrary code via bytecode rewriting at the /guardrails/test_custom_code URI.

Why this priority

High severity
EPSS top 3%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	15.5% (top 3%)
CISA exploited list	No
Weakness	CWE-420, CWE-94
Published	2026-04-10
Last modified	2026-10-26

Publisher (CNA): MITRE · Vendor: litellm

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

Am I affected?

Timeline

2026-04-10 14:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

litellm litellm UPGRADE

Affected: <= 2026-04-08

Fixed in: newer than 2026-04-08

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 2026-04-08 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade litellm

Note

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

Exact fixes by distribution

Python (pip) · litellm · FIXED · 1.83.10 · vulnerable: >= 1.81.8, < 1.83.10 · source

pip install --upgrade "litellm>=1.83.10" pip show litellm

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: learner202649/CVE-2026-40217-PoC (0 stars)
Write-up: www.x41-dsec.de/lab/advisories/x41-2026-001-litellm/
Nuclei scan template: LiteLLM < 1.25.0 - Remote Code Execution

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-2026-40217?

litellm: upgrade to newer than 2026-04-08. Exact commands for each OS are on this page.

Is CVE-2026-40217 being exploited?

CVE-2026-40217 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-2026-40217 affect?

CVE-2026-40217 affects litellm. Severity is high (CVSS 8.8). LiteLLM through 2026-04-08 allows remote attackers to execute arbitrary code via bytecode rewriting at the /guardrails/test_custom_code URI.

How urgent is CVE-2026-40217?

Priority 60/100. High severity; EPSS top 3%: very likely to be exploited; Public exploit reference

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References

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