Forge: ReDoS in forge.http response header and cookie trimming
`forge.http` trims response header and `Set-Cookie` values with the regular expression `/\s*$/`, which takes quadratic time on a long run of whitespace followed by another character. A server or on-path attacker can block a `forge.http` client for minutes with one large response header. Fixed in node-forge 1.4.3.
### Details
`_trimString()` in `lib/http.js` removes trailing whitespace with `str.replace(/\s*$/, '')`. On a string of n whitespace characters followed by a non-whitespace character, the regular expression engine tries a match at each of the n positions and scans the rest of the run each time, so the work is O(n^2). `forge.http` calls `_trimString()` on every response header value read by `response.readHeader()`, and again on cookie names and values in `response.getCookies()`. There is no limit on header size.
With Node.js 24, an 80 KB header value takes about 4 seconds to parse, and 1 MB about 10 minutes, during which the event loop (or browser tab) is blocked.
`forge.http` is not loaded by `require('node-forge')`. It is part of the `forge.all` bundle and needs a socket pool provided by the application (historically Flash sockets via `forge.xhr`), so few applications use it.
The fix trims trailing whitespace with a loop, as `lib/pem.js` has done since 1.4.1. The trimmed result is unchanged.
#### Patches
Fixed in node-forge 1.4.3.
#### Workarounds
Limit the size of HTTP response headers before passing them to `forge.http`, for example in the socket pool's data handler.
#### Resources
- Related: GHSA-7wch-p9px-956x (ReDoS in PEM decoding, fixed in 1.4.1): https://github.com/digitalbazaar/forge/security/advisories/GHSA-7wch-p9px-956x
#### Severity
CVSS 3.1: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (5.9, Moderate)
CVSS 4.0 (informational): CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N (8.2)
CVSS 4.0 has no counterpart to 3.1's AC:H beyond AT:P and scores this higher; the severity rating follows CVSS 3.1.
#### Credits
Reported by @manus-pi.
### Proof of concept
var response = forge.http.createResponse();
var ws = new Array(40001).join('\t ');
response.readHeader(forge.util.createBuffer(
'HTTP/1.1 200 OK\r\nX-A: a' + ws + 'X\r\n\r\n'));
// <= 1.4.2: about 4 seconds (quadratic in the whitespace length)
// 1.4.3: about 1 ms
Regression tests are in tests/security/ghsa-6cv4-p8m7-4r25.js.
### Impact
Applications that use `forge.http` to talk to servers they don't control are affected. The server, or an on-path attacker, can send a response header that blocks the client's event loop for minutes, denying service to everything else in the process. There is no confidentiality or integrity impact.
- Source published
- 10 Nov 2026 21:16:22 UTC
- Source modified
- 10 Nov 2026 21:30:03 UTC
- Saved here
- 10 Nov 2026 22:21:40 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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Publisher rating · MODERATE