Forge: Regular expression denial of service in PEM decoding (pem.decode)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

29 Oct 2026 18:45:55 UTC

Source modified

29 Oct 2026 20:23:11 UTC

Observed here

29 Oct 2026 21:48:56 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Source published

Oct 29, 2026, 6:45:55 PM (timezone not stated)

Source modified

Oct 29, 2026, 8:23:11 PM (timezone not stated)

Observed here

6 Nov 2026 01:44:34 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Source published

29 Oct 2026 19:17:20 UTC

Source modified

30 Oct 2026 17:18:03 UTC

Observed here

30 Oct 2026 23:47:40 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

### 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. There is no confidentiality or integrity impact.

Source published

30 Oct 2026 23:02:25 UTC

Source modified

30 Oct 2026 23:15:07 UTC

Observed here

30 Oct 2026 23:45:44 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH