How severe is CVE-2026-31943?

CVE-2026-31943 has a CVSS 3.x base score of 8.5, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2026-31943 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-31943?

CVE-2026-31943 primarily affects Librechat. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-31943?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-31943 have an EU (EUVD) identifier?

Yes. CVE-2026-31943 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16764.

When was CVE-2026-31943 published?

CVE-2026-31943 was published on 2026-03-27 and last updated on 2026-06-17.

CVE-2026-31943

CVE-2026-31943 is a high-severity vulnerability in Librechat with a CVSS 3.x base score of 8.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-918.

Key facts

Severity: High (CVSS 3.x base score 8.5)
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-16764
Weakness: CWE-918
Affected product: Librechat
Published: 2026-03-27
Last modified: 2026-06-17

Description

LibreChat is a ChatGPT clone with additional features. Prior to version 0.8.3, `isPrivateIP()` in `packages/api/src/auth/domain.ts` fails to detect IPv4-mapped IPv6 addresses in their hex-normalized form, allowing any authenticated user to bypass SSRF protection and make the server issue HTTP requests to internal network resources — including cloud metadata services (e.g., AWS `169.254.169.254`), loopback, and RFC1918 ranges. Version 0.8.3 fixes the issue.

Frequently asked questions

What is CVE-2026-31943?: LibreChat is a ChatGPT clone with additional features. Prior to version 0.8.3, `isPrivateIP()` in `packages/api/src/auth/domain.ts` fails to detect IPv4-mapped IPv6 addresses in their hex-normalized form, allowing any authenticated user to bypass SSRF protection and make the server issue HTTP requests to internal network resources — including cloud metadata services (e.g., AWS `169.254.169.254`), loopback, and RFC1918 ranges. Version 0.8.3 fixes the issue.
How severe is CVE-2026-31943?: CVE-2026-31943 has a CVSS 3.x base score of 8.5, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2026-31943 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-31943?: CVE-2026-31943 primarily affects Librechat. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-31943?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-31943 have an EU (EUVD) identifier?: Yes. CVE-2026-31943 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16764.
When was CVE-2026-31943 published?: CVE-2026-31943 was published on 2026-03-27 and last updated on 2026-06-17.

References

https://github.com/danny-avila/LibreChat/security/advisories/GHSA-w5r7-4f94-vp4c

Affected products (3)

cpe:2.3:a:librechat:librechat:*:*:*:*:*:*:*:*
cpe:2.3:a:librechat:librechat:0.8.3:rc1:*:*:*:*:*:*
cpe:2.3:a:librechat:librechat:0.8.3:rc2:*:*:*:*:*:*

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