Skip to main content
VulnerabilityPublished

CVE-2026-55603: chimurai http-proxy-middleware · CRLF Injection

Affects chimurai http-proxy-middlewareSource CVE Database V5

0
Compare

Not known to be exploited · CVSS 7.5 High : upgrade to 4.1.1 or 3.0.7 soon.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.1.1, 3.0.7
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

What to do

Upgrade chimurai http-proxy-middleware to 4.1.1 or 3.0.7.

Affected software

ProductAffectedFixed in
chimuraihttp-proxy-middlewareAffected
  • >=4.0.0 <4.1.1
Fixed in
  • 4.1.1
chimuraihttp-proxy-middlewareAffected
  • >=3.0.4 <3.0.7
Fixed in
  • 3.0.7
npmhttp-proxy-middlewarepkg:npm/http-proxy-middlewareOther threatsAffected
  • <3.0.7
  • <4.1.1
Fixed in
  • 3.0.7
  • 4.1.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade http-proxy-middleware to version 3.0.7 or later, or 4.1.1 or later, where this vulnerability is fixed. Patch status is not explicitly stated but the description confirms the vulnerability is fixed starting at these versions. Until upgraded, avoid using the fixRequestBody() helper with multipart/form-data content types or apply custom input validation to neutralize CRLF sequences in request keys and values.

Description

http-proxy-middleware is node.js http-proxy middleware. From 3.0.4 until 3.0.7 and 4.1.1, fixRequestBody() is the library's documented helper for re-emitting a request body that was already consumed by a body parser. When the outgoing Content-Type is multipart/form-data, it rebuilds the body with handlerFormDataBodyData(), which interpolates each req.body key and value directly into the multipart wire format without neutralizing CR/LF. A \r\n inside a value (or key) lets an attacker close the current part and inject an entirely new form part. Because the proxy's own body parser saw a single opaque value, any gateway-side policy or validation performed on req.body is evaluated against a different set of fields than the upstream backend ultimately parses a request/parameter desynchronization across the trust boundary. This vulnerability is fixed in 3.0.7 and 4.1.1.

References

Community reviews

Loading reviews…