CWE-1241
AllowedUse of Predictable Algorithm in Random Number Generator
Abstraction: Base · Status: Draft
The device uses an algorithm that is predictable and generates a pseudo-random number.
15 vulnerabilities reference this CWE, most recent first.
GHSA-97W9-GCC7-VR8G
Vulnerability from github – Published: 2022-11-16 12:00 – Updated: 2023-07-19 19:58A vulnerability, which was classified as problematic, was found in phpservermon. This affects the function generatePasswordResetToken of the file src/psm/Service/User.php. The manipulation leads to use of predictable algorithm in random number generator. The exploit has been disclosed to the public and may be used. The name of the patch is 3daa804d5f56c55b3ae13bfac368bb84ec632193. It is recommended to apply a patch to fix this issue. The identifier VDB-213717 was assigned to this vulnerability.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "phpservermon/phpservermon"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-4240"
],
"database_specific": {
"cwe_ids": [
"CWE-1241",
"CWE-330",
"CWE-331"
],
"github_reviewed": true,
"github_reviewed_at": "2023-07-07T19:27:56Z",
"nvd_published_at": "2022-11-15T23:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability, which was classified as problematic, was found in phpservermon. This affects the function `generatePasswordResetToken` of the file `src/psm/Service/User.php`. The manipulation leads to use of predictable algorithm in random number generator. The exploit has been disclosed to the public and may be used. The name of the patch is 3daa804d5f56c55b3ae13bfac368bb84ec632193. It is recommended to apply a patch to fix this issue. The identifier VDB-213717 was assigned to this vulnerability.",
"id": "GHSA-97w9-gcc7-vr8g",
"modified": "2023-07-19T19:58:50Z",
"published": "2022-11-16T12:00:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-4240"
},
{
"type": "WEB",
"url": "https://github.com/phpservermon/phpservermon/commit/3daa804d5f56c55b3ae13bfac368bb84ec632193"
},
{
"type": "PACKAGE",
"url": "https://github.com/phpservermon/phpservermon"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/2-phpservermon/phpservermon"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.213717"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Insufficient Entropy in PHPServerMon PRNG"
}
GHSA-FQR3-6HFC-HRF6
Vulnerability from github – Published: 2026-02-19 18:31 – Updated: 2026-02-19 18:31The Popup Builder – Create highly converting, mobile friendly marketing popups. plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 4.4.2. This is due to the plugin generating predictable unsubscribe tokens using deterministic data. This makes it possible for unauthenticated attackers to unsubscribe arbitrary subscribers from mailing lists via brute-forcing the unsubscribe token, granted they know the victim's email address
{
"affected": [],
"aliases": [
"CVE-2025-13079"
],
"database_specific": {
"cwe_ids": [
"CWE-1241"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-19T07:17:29Z",
"severity": "MODERATE"
},
"details": "The Popup Builder \u2013 Create highly converting, mobile friendly marketing popups. plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 4.4.2. This is due to the plugin generating predictable unsubscribe tokens using deterministic data. This makes it possible for unauthenticated attackers to unsubscribe arbitrary subscribers from mailing lists via brute-forcing the unsubscribe token, granted they know the victim\u0027s email address",
"id": "GHSA-fqr3-6hfc-hrf6",
"modified": "2026-02-19T18:31:49Z",
"published": "2026-02-19T18:31:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-13079"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/popup-builder/tags/4.4.2/com/classes/Actions.php#L842"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/popup-builder/tags/4.4.2/com/helpers/AdminHelper.php#L896"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026old=3444540%40popup-builder\u0026new=3444540%40popup-builder\u0026sfp_email=\u0026sfph_mail="
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/62b29721-0580-4e1d-824d-9b8355890248?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HC4J-7MQG-CXJJ
Vulnerability from github – Published: 2022-11-16 12:00 – Updated: 2023-07-07 21:05A vulnerability, which was classified as problematic, was found in phpservermon. Affected is the function setUserLoggedIn of the file src/psm/Service/User.php. The manipulation leads to use of predictable algorithm in random number generator. The exploit has been disclosed to the public and may be used. The name of the patch is bb10a5f3c68527c58073258cb12446782d223bc3. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-213744.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "phpservermon/phpservermon"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-4241"
],
"database_specific": {
"cwe_ids": [
"CWE-1241",
"CWE-330",
"CWE-331"
],
"github_reviewed": true,
"github_reviewed_at": "2023-07-07T21:05:46Z",
"nvd_published_at": "2022-11-15T23:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability, which was classified as problematic, was found in phpservermon. Affected is the function `setUserLoggedIn` of the file `src/psm/Service/User.php`. The manipulation leads to use of predictable algorithm in random number generator. The exploit has been disclosed to the public and may be used. The name of the patch is bb10a5f3c68527c58073258cb12446782d223bc3. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-213744.",
"id": "GHSA-hc4j-7mqg-cxjj",
"modified": "2023-07-07T21:05:46Z",
"published": "2022-11-16T12:00:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-4241"
},
{
"type": "WEB",
"url": "https://github.com/phpservermon/phpservermon/commit/bb10a5f3c68527c58073258cb12446782d223bc3"
},
{
"type": "PACKAGE",
"url": "https://github.com/phpservermon/phpservermon"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/1-phpservermon/phpservermon"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.213744"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "PHPServerMon PRNG has Insufficient Entropy"
}
GHSA-Q8W6-W55C-CCV5
Vulnerability from github – Published: 2026-05-11 14:42 – Updated: 2026-05-11 14:42CVE-2026-6420: Hardcoded attestation challenge nonce allows replay attacks
Impact
The CertificationParameters.generate_challenge() method in the push attestation protocol uses a hardcoded challenge nonce instead of generating a cryptographically random value. This removes the nonce-based replay protection from TPM quote attestation.
An attacker with root access on a monitored agent node can exploit this by stockpiling valid TPM quotes (using tpm2_quote with the known nonce) before compromising the system, then replaying them to evade detection by the verifier. The push attestation timeout (~10s) constrains the generation window, but TPM throughput allows stockpiling ~50-200 quotes, enabling approximately 8-33 minutes of undetected compromise with default settings.
The attack is limited to a single agent node (AK signature binding prevents cross-agent replay). The pull-mode (legacy) attestation path is not affected.
Affected versions: >= 7.14.0, <= 7.14.1
CVSS: 6.3 Medium (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L)
| Metric | Value | Rationale |
|---|---|---|
| AV | Local | Exploitation requires local access to the agent machine (stop agent, access TPM, run replacement). The network transmission of quotes to the verifier is normal protocol operation. |
| AC | Low | Deterministic attack: publicly visible nonce, standard tpm2-tools, no race conditions. |
| PR | High | Root on a legitimate enrolled node is required. The vulnerability does not help gain access -- it only helps evade detection after root is obtained. No value against a machine the attacker already controls. |
| UI | None | Fully automated after initial setup. |
| S | Unchanged | AK signature binding confines impact to the single compromised agent. |
| C | High | Compromised node continues receiving bootstrap keys, payloads, and secrets intended for trusted nodes. |
| I | High | Verifier cannot distinguish a healthy system from a fully compromised one during the evasion window. |
| A | Low | Only the compromised agent's revocation and incident response are suppressed; the system as a whole remains operational. |
The base score does not fully capture the operational severity: Keylime exists to detect machine compromise, so 8-33 minutes of undetected compromise is operationally critical. The fix is a one-line change and should be applied immediately regardless of the base score.
Patches
The fix restores the original random nonce generation (one-line change in keylime/models/verifier/evidence.py):
# Before (vulnerable):
def generate_challenge(self, bit_length):
# self.challenge = Nonce.generate(bit_length)
self.challenge = bytes.fromhex("49beed365aac777dae23564f5ad0ec")
# After (fixed):
def generate_challenge(self, bit_length):
self.challenge = Nonce.generate(bit_length)
Users should upgrade to the version containing this fix (7.14.2).
Workarounds
There is no complete workaround. The following existing mechanisms provide partial mitigation and are already active by default (no configuration needed):
- TPM clock monotonicity check limits each distinct stockpiled quote to a single use, bounding the total evasion time.
- Push attestation timeout (default 10s) prevents the attacker from going silent and constrains the quote generation window.
Reducing quote_interval increases the attestation frequency but does not prevent the stockpiling attack.
References
- CWE-329: Generation of Predictable IV/Nonce (primary -- hardcoded nonce in cryptographic attestation protocol)
- CWE-547: Use of Hard-Coded, Security-relevant Constants (hardcoded constant left in production code)
- CWE-294: Authentication Bypass by Capture-replay (consequence -- enables replay attacks)
- CWE-1241: Use of Predictable Algorithm in Random Number Generator
- Introducing commit:
2bf91197via PR #1814 - TCG TPM 2.0 Library Specification, Part 1, Section 18.4 (TPM2_Quote)
- IETF RATS Architecture (RFC 9334), Section 8 (Freshness)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 7.14.1"
},
"package": {
"ecosystem": "PyPI",
"name": "keylime"
},
"ranges": [
{
"events": [
{
"introduced": "7.14.0"
},
{
"fixed": "7.14.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-6420"
],
"database_specific": {
"cwe_ids": [
"CWE-1241",
"CWE-294",
"CWE-329",
"CWE-547"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-11T14:42:46Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## CVE-2026-6420: Hardcoded attestation challenge nonce allows replay attacks\n\n### Impact\n\nThe `CertificationParameters.generate_challenge()` method in the push attestation protocol uses a hardcoded challenge nonce instead of generating a cryptographically random value. This removes the nonce-based replay protection from TPM quote attestation.\n\nAn attacker with root access on a monitored agent node can exploit this by stockpiling valid TPM quotes (using `tpm2_quote` with the known nonce) before compromising the system, then replaying them to evade detection by the verifier. The push attestation timeout (~10s) constrains the generation window, but TPM throughput allows stockpiling ~50-200 quotes, enabling approximately 8-33 minutes of undetected compromise with default settings.\n\nThe attack is limited to a single agent node (AK signature binding prevents cross-agent replay). The pull-mode (legacy) attestation path is not affected.\n\n**Affected versions:** \u003e= 7.14.0, \u003c= 7.14.1\n\n**CVSS:** 6.3 Medium (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L`)\n\n| Metric | Value | Rationale |\n|---|---|---|\n| AV | Local | Exploitation requires local access to the agent machine (stop agent, access TPM, run replacement). The network transmission of quotes to the verifier is normal protocol operation. |\n| AC | Low | Deterministic attack: publicly visible nonce, standard `tpm2-tools`, no race conditions. |\n| PR | High | Root on a legitimate enrolled node is required. The vulnerability does not help gain access -- it only helps evade detection after root is obtained. No value against a machine the attacker already controls. |\n| UI | None | Fully automated after initial setup. |\n| S | Unchanged | AK signature binding confines impact to the single compromised agent. |\n| C | High | Compromised node continues receiving bootstrap keys, payloads, and secrets intended for trusted nodes. |\n| I | High | Verifier cannot distinguish a healthy system from a fully compromised one during the evasion window. |\n| A | Low | Only the compromised agent\u0027s revocation and incident response are suppressed; the system as a whole remains operational. |\n\nThe base score does not fully capture the operational severity: Keylime exists to detect machine compromise, so 8-33 minutes of undetected compromise is operationally critical. The fix is a one-line change and should be applied immediately regardless of the base score.\n\n### Patches\n\nThe fix restores the original random nonce generation (one-line change in `keylime/models/verifier/evidence.py`):\n\n```python\n# Before (vulnerable):\ndef generate_challenge(self, bit_length):\n # self.challenge = Nonce.generate(bit_length)\n self.challenge = bytes.fromhex(\"49beed365aac777dae23564f5ad0ec\")\n\n# After (fixed):\ndef generate_challenge(self, bit_length):\n self.challenge = Nonce.generate(bit_length)\n```\n\nUsers should upgrade to the version containing this fix (7.14.2).\n\n### Workarounds\n\nThere is no complete workaround. The following existing mechanisms provide partial mitigation and are already active by default (no configuration needed):\n\n1. **TPM clock monotonicity check** limits each distinct stockpiled quote to a single use, bounding the total evasion time.\n2. **Push attestation timeout** (default 10s) prevents the attacker from going silent and constrains the quote generation window.\n\nReducing `quote_interval` increases the attestation frequency but does not prevent the stockpiling attack.\n\n### References\n\n- CWE-329: Generation of Predictable IV/Nonce (primary -- hardcoded nonce in cryptographic attestation protocol)\n- CWE-547: Use of Hard-Coded, Security-relevant Constants (hardcoded constant left in production code)\n- CWE-294: Authentication Bypass by Capture-replay (consequence -- enables replay attacks)\n- CWE-1241: Use of Predictable Algorithm in Random Number Generator\n- Introducing commit: [`2bf91197`](https://github.com/keylime/keylime/commit/2bf91197) via [PR #1814](https://github.com/keylime/keylime/pull/1814)\n- TCG TPM 2.0 Library Specification, Part 1, Section 18.4 (TPM2_Quote)\n- IETF RATS Architecture (RFC 9334), Section 8 (Freshness)",
"id": "GHSA-q8w6-w55c-ccv5",
"modified": "2026-05-11T14:42:46Z",
"published": "2026-05-11T14:42:46Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/keylime/keylime/security/advisories/GHSA-q8w6-w55c-ccv5"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6420"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-6420"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2458889"
},
{
"type": "PACKAGE",
"url": "https://github.com/keylime/keylime"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "Keylime has a hardcoded attestation challenge nonce that allows replay attacks"
}
GHSA-WC6P-4GWJ-JCR8
Vulnerability from github – Published: 2026-05-06 12:30 – Updated: 2026-06-24 03:30Duplicate Advisory
This advisory has been withdrawn because it is a duplicate of GHSA-q8w6-w55c-ccv5. This link is maintained to preserve external references.
Original Description
A flaw was found in Keylime. An attacker with root access on an enrolled monitored machine, where the Keylime agent runs, can exploit a vulnerability in the Keylime verifier. The verifier uses a hardcoded challenge nonce for Trusted Platform Module (TPM) quote attestation instead of a cryptographically random value. This allows the attacker to stockpile valid TPM quotes and replay them to evade detection after compromising the system. This issue affects only the push model deployment.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 7.14.1"
},
"package": {
"ecosystem": "PyPI",
"name": "keylime"
},
"ranges": [
{
"events": [
{
"introduced": "7.14.0"
},
{
"fixed": "7.14.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-1241"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-11T14:08:50Z",
"nvd_published_at": "2026-05-06T11:16:05Z",
"severity": "MODERATE"
},
"details": "### Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-q8w6-w55c-ccv5. This link is maintained to preserve external references.\n\n### Original Description\nA flaw was found in Keylime. An attacker with root access on an enrolled monitored machine, where the Keylime agent runs, can exploit a vulnerability in the Keylime verifier. The verifier uses a hardcoded challenge nonce for Trusted Platform Module (TPM) quote attestation instead of a cryptographically random value. This allows the attacker to stockpile valid TPM quotes and replay them to evade detection after compromising the system. This issue affects only the push model deployment.",
"id": "GHSA-wc6p-4gwj-jcr8",
"modified": "2026-06-24T03:30:34Z",
"published": "2026-05-06T12:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6420"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:28582"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-6420"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2458889"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "Duplicate Advisory: Keylime has a hardcoded attestation challenge nonce that allows replay attacks",
"withdrawn": "2026-05-11T14:08:50Z"
}
Mitigation
It is highly recommended to use a true random number generator (TRNG) to ensure the security of encryption schemes. Hardware-based TRNGs generate unpredictable, unbiased, and independent random numbers because they employ physical phenomena, e.g., electrical noise, as sources to generate random numbers.
Mitigation
It is highly recommended to use a true random number generator (TRNG) to ensure the security of encryption schemes. Hardware-based TRNGs generate unpredictable, unbiased, and independent random numbers because they employ physical phenomena, e.g., electrical noise, as sources to generate random numbers.
CAPEC-97: Cryptanalysis
Cryptanalysis is a process of finding weaknesses in cryptographic algorithms and using these weaknesses to decipher the ciphertext without knowing the secret key (instance deduction). Sometimes the weakness is not in the cryptographic algorithm itself, but rather in how it is applied that makes cryptanalysis successful. An attacker may have other goals as well, such as: Total Break (finding the secret key), Global Deduction (finding a functionally equivalent algorithm for encryption and decryption that does not require knowledge of the secret key), Information Deduction (gaining some information about plaintexts or ciphertexts that was not previously known) and Distinguishing Algorithm (the attacker has the ability to distinguish the output of the encryption (ciphertext) from a random permutation of bits).