LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader
cve-program · CVE-2026-27795
PublishedLangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.
Read the publisher's advisoryeuvd · EUVD-2026-8697
PublishedLangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.
Read the publisher's advisorynvd · CVE-2026-27795
PublishedLangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.
Read the publisher's advisoryosv · GHSA-mphv-75cg-56wg
Published## Summary A redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). ## Affected Component - Package: `@langchain/community` - Component: `RecursiveUrlLoader` - Configuration: `preventOutside` (default: `true`) is insufficient to prevent this bypass when redirects are followed automatically. ## Description `RecursiveUrlLoader` is a web crawler that recursively follows links from a starting URL. The existing SSRF mitigation validates the initial URL before fetching, but it does not re-validate when the request follows redirects. Because fetch follows redirects by default, an attacker can supply a public URL that passes validation and then redirects to a private network address, localhost, or cloud metadata endpoint. This constitutes a “check‑then‑act” gap in the request lifecycle: the safety check occurs before the redirect chain is resolved, and the final destination is never validated. ## Impact If an attacker can influence content on a page being crawled (e.g., user‑generated content, untrusted external pages), they can cause the crawler to: - Fetch cloud instance metadata (AWS, GCP, Azure), potentially exposing credentials or tokens - Access internal services on private networks (`10.x`, `172.16.x`, `192.168.x`) - Connect to localhost services - Exfiltrate response data through attacker-controlled redirect chains This is exploitable in any environment where `RecursiveUrlLoader` runs with access to internal networks or metadata services, which includes most cloud-hosted deployments. ## Attack Scenario 1. The crawler is pointed at a public URL that passes initial SSRF validation. 2. That URL responds with a 3xx redirect to an internal target. 3. The fetch follows the redirect automatically without revalidation. 4. The crawler accesses the internal or metadata endpoint. Example redirector: ``` https://302.r3dir.me/--to/?url=http://169.254.169.254/latest/meta-data/ ``` ## Root Cause - SSRF validation (`validateSafeUrl`) is only performed on the initial URL. - Redirects are followed automatically by fetch (`redirect: "follow"` default), so the request can change destinations without additional validation. ## Resolution Upgrade to `@langchain/community` **>= 1.1.18**, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. - Automatic redirects are disabled (`redirect: "manual"`). - Each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request. - A maximum redirect limit prevents infinite loops. ## Reources - Original SSRF fix (CVE-2026-26019): enforced origin comparison and added initial URL validation - https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
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cve-program · CVE-2026-27795
PublishedLangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader
LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.
- Source published
- 25 Feb 2026 17:30:01 UTC
- Source modified
- 25 Feb 2026 18:42:52 UTC
- Saved here
- 23 Oct 2026 15:48:27 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 4.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N
euvd · EUVD-2026-8697
PublishedLangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial UR…
LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.
Additional publisher context
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Feb 25, 2026, 5:30:01 PM
dateUpdated: Feb 25, 2026, 6:42:52 PM
- Source published
- Feb 25, 2026, 5:30:01 PM (timezone not stated)
- Source modified
- Feb 25, 2026, 6:42:52 PM (timezone not stated)
- Saved here
- 13 Nov 2026 15:59:18 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
EUVD CVSS 3.1 · 4.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N
nvd · CVE-2026-27795
PublishedLangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial UR…
LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.
Additional publisher context
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Analyzed
Weakness classifications: CWE-918
Original publisher date fields
published: 2026-02-25T18:23:41.153
lastModified: 2026-06-17T10:27:41.753
1 source CPE criteria · context only
- cpe:2.3:a:langchain:langchain_community:*:*:*:*:*:node.js:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
- Source published
- 25 Feb 2026 18:23:41 UTC
- Source modified
- 17 Jun 2026 10:27:41 UTC
- Saved here
- 25 Oct 2026 06:17:33 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · [email protected] · Secondary · 4.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N
CVSS 3.1 · [email protected] · Primary · 7.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
osv · GHSA-mphv-75cg-56wg
PublishedLangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader
## Summary A redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). ## Affected Component - Package: `@langchain/community` - Component: `RecursiveUrlLoader` - Configuration: `preventOutside` (default: `true`) is insufficient to prevent this bypass when redirects are followed automatically. ## Description `RecursiveUrlLoader` is a web crawler that recursively follows links from a starting URL. The existing SSRF mitigation validates the initial URL before fetching, but it does not re-validate when the request follows redirects. Because fetch follows redirects by default, an attacker can supply a public URL that passes validation and then redirects to a private network address, localhost, or cloud metadata endpoint. This constitutes a “check‑then‑act” gap in the request lifecycle: the safety check occurs before the redirect chain is resolved, and the final destination is never validated. ## Impact If an attacker can influence content on a page being crawled (e.g., user‑generated content, untrusted external pages), they can cause the crawler to: - Fetch cloud instance metadata (AWS, GCP, Azure), potentially exposing credentials or tokens - Access internal services on private networks (`10.x`, `172.16.x`, `192.168.x`) - Connect to localhost services - Exfiltrate response data through attacker-controlled redirect chains This is exploitable in any environment where `RecursiveUrlLoader` runs with access to internal networks or metadata services, which includes most cloud-hosted deployments. ## Attack Scenario 1. The crawler is pointed at a public URL that passes initial SSRF validation. 2. That URL responds with a 3xx redirect to an internal target. 3. The fetch follows the redirect automatically without revalidation. 4. The crawler accesses the internal or metadata endpoint. Example redirector: ``` https://302.r3dir.me/--to/?url=http://169.254.169.254/latest/meta-data/ ``` ## Root Cause - SSRF validation (`validateSafeUrl`) is only performed on the initial URL. - Redirects are followed automatically by fetch (`redirect: "follow"` default), so the request can change destinations without additional validation. ## Resolution Upgrade to `@langchain/community` **>= 1.1.18**, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. - Automatic redirects are disabled (`redirect: "manual"`). - Each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request. - A maximum redirect limit prevents infinite loops. ## Reources - Original SSRF fix (CVE-2026-26019): enforced origin comparison and added initial URL validation - https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7
- Source published
- 25 Feb 2026 22:59:48 UTC
- Source modified
- 10 Sep 2026 03:50:35 UTC
- Saved here
- 24 Oct 2026 13:17:17 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N
Publisher rating · MODERATE