CVE-2026-118779

Forge (also called node-forge) is a native implementation of Transport Layer Security in JavaScript. Prior to 1.4.1, the affected implementation used pem.decode(), lib/pem.js, missing END line to process the relevant input or security decision. node-forge used polynomial-time regular expressions in pem.decode(), including when searching for a matching END line and parsing encapsulated headers. An unauthenticated attacker able to supply PEM input to any high-level parser could consume excessive CPU with a long malformed message and cause denial of service. This issue is fixed in version 1.4.1.

Forge (also called node-forge) is a native implementation of Transport Layer Security in JavaScript. Prior to 1.4.1, the affected implementation used pem.decode(), lib/pem.js, missing END line to process the relevant input or security decision. node-forge used polynomial-time regular expressions in pem.decode(), including when searching for a matching END line and parsing encapsulated headers. An unauthenticated attacker able to supply PEM input to any high-level parser could consume excessive CPU with a long malformed message and cause denial of service. This issue is fixed in version 1.4.1.

Summary

pem.decode(), which every node-forge API that parses PEM input uses, split messages with a regular expression that takes polynomial time on input without a matching END line, and parsed encapsulated headers with regular expressions that take quadratic time on long header lines. A remote attacker can block the Node.js event loop for seconds to minutes with a crafted input of a few tens of kilobytes. Fixed in node-forge 1.4.1.

Details

pem.decode() in lib/pem.js found PEM messages with this regular expression:

/\s*-----BEGIN ([A-Z0-9- ]+)-----\r?\n?([\x21-\x7e\s]+?(?:\r?\n\r?\n))?([:A-Za-z0-9+\/=\s]+?)-----END \1-----/g

The optional headers group and the body group are adjacent, lazy, and share characters (whitespace and the base64 alphabet), and the match must end with an END line whose label equals the BEGIN label (\1). When no such END line follows, the engine tries every split of the text between the two groups, for every label split and at every BEGIN line in the input. The work grows polynomially with the input length (roughly cubic for repeated BEGIN/END lines with mismatched labels, quadratic for a BEGIN line followed by many newlines).

The encapsulated header parsing in the same function had two smaller quadratic cases: trimming each header line with /\s+$/, and an unanchored header regex ([\x21-\x7e]+):... that retries at every position of a long line without a colon. These are reachable when a message does match.

All PEM entry points call pem.decode(), including pki.certificateFromPem(), pki.privateKeyFromPem(), pki.publicKeyFromPem(), pki.certificationRequestFromPem(), pki.encryptedPrivateKeyFromPem(), pki.decryptRsaPrivateKey() and pkcs7.messageFromPem().

The fix replaces the message regular expression with a scanner that indexes the END lines once and matches each BEGIN line in linear time, finding the same messages as before. The one difference: a label containing ----- (-----BEGIN A-----B-----) was matched as A-----B if possible; now only the shortest label, A, is used. RFC 7468 labels can't contain --. Header parsing now trims lines with a loop and only starts a header match at the beginning of a run of printable characters, which gives the same result.

Patches

Fixed in node-forge 1.4.1. PEM messages and encapsulated headers are now parsed in linear time.

Workarounds

Rejecting untrusted PEM input larger than a few kilobytes before passing it to node-forge limits the delay but doesn't remove it: on 1.4.0, about 7 KB of crafted input blocked for 0.4 s, and 29 KB for 24 s.

Credits

Reported by Ahmed Mokhtari (@AhmedMokhtari), @mwlik and @imenyoo2, and independently by @offset, @bibu123456 (coordinated by @Kayiz-PT), and @Mucahic.

Proof of concept

var forge = require('node-forge');
var pem = ' -----BEGIN I-----G-----END B'.repeat(1000) + '\x00'; // 29 KB
try {
  forge.pki.certificateFromPem(pem);
} catch(e) {}

On 1.4.0 (Node.js 24) this call blocks for about 24 seconds before throwing "Invalid PEM formatted message."; 14 KB takes about 3 seconds. A BEGIN line followed by 32 KB of newlines and no END line takes about 1.5 seconds, and the time grows quadratically from there. On 1.4.1 each of these inputs is rejected in a few milliseconds, and 1 MB inputs of any of these shapes take under 100 ms.

The PoC is in tests/pocs/ghsa-7wch-p9px-956x.js. Regression tests are in tests/unit/pem.js ("GHSA-7wch-p9px-956x ReDoS checks").

Impact

Any application that passes untrusted PEM text to node-forge is affected: for example, services that accept uploaded certificates, keys or certificate signing requests, or that parse certificates from configuration, SAML metadata or other user-supplied documents. A remote, unauthenticated attacker can send a small crafted input that blocks the Node.js event loop for seconds to minutes per request, so the process stops serving other requests. Repeated requests keep it unavailable.…

Impact

The regex used for the forge.util.parseUrl API would not properly parse certain inputs resulting in a parsed data structure that could lead to undesired behavior.

Patches

forge.util.parseUrl and other very old related URL APIs were removed in 1.0.0 in favor of letting applications use the more modern WHATWG URL Standard API.

Workarounds

Ensure code does not directly or indirectly call forge.util.parseUrl with untrusted input.

References

• https://www.huntr.dev/bounties/41852c50-3c6d-4703-8c55-4db27164a4ae/

For more information

If you have any questions or comments about this advisory:

• Open an issue in forge
• Email us at [email protected]

Forge (also called node-forge) is a native implementation of Transport Layer Security in JavaScript. Prior to 1.4.1, the affected implementation used pem.decode(), lib/pem.js, missing END line to process the relevant input or security decision. node-forge used polynomial-time regular expressions in pem.decode(), including when searching for a matching END line and parsing encapsulated headers. An unauthenticated attacker able to supply PEM input to any high-level parser could consume excessive CPU with a long malformed message and cause denial of service. This issue is fixed in version 1.4.1.

Forge (also called node-forge) is a native implementation of Transport Layer Security in JavaScript. Prior to 1.4.1, the affected implementation used pem.decode(), lib/pem.js, missing END line to process the relevant input or security decision. node-forge used polynomial-time regular expressions in pem.decode(), including when searching for a matching END line and parsing encapsulated headers. An unauthenticated attacker able to supply PEM input to any high-level parser could consume excessive CPU with a long malformed message and cause denial of service. This issue is fixed in version 1.4.1.