CriticalCVE-2024-58136

    Yiiframework Yii Improper Protection of Alternate Path Vulnerability (CVE-2024-58136)

    Published In CISA KEV since Sources: pwn.watch, CVE.org, OSV

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    What is affected, what to do

    The vulnerability CVE-2024-58136 in the Yii Framework allows for remote code execution (RCE) due to insufficient protection against alternate paths. An attacker can execute arbitrary code remotely, leading to full control over the affected system. This vulnerability is actively exploited in the wild, as confirmed by its listing in the CISA KEV catalog. Affected are all Yii 2 versions before 2.0.52 and products implementing Yii, such as Craft CMS. An immediate upgrade to version 2.0.52 or higher is urgently required to mitigate this vulnerability.

    The vulnerability is being actively exploited; treat it as a priority. Update Yii to version 2.0.52. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Yii lt 2..2.0.52
    Fixed in
    • Yii 2.0.52

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    9.0

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: pwn.watch, CVE.org, OSV

    87.8 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.76

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    233.05 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.0
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    87.8 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.76
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 2 May 2025
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-424

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This CVE sits on KEV because it is network-reachable without authentication, grants remote code execution, and was actively exploited against Craft CMS and other Yii-based applications between February and April 2025 — it is a regression of the previously known CVE-2024-4990. Exploitation likelihood is among the very highest tracked by EPSS and working exploits are public. For NIS2-regulated organisations running internet-facing PHP applications (CMS portals, customer portals, APIs) this is a P1 patch; internal-only Yii apps behind authentication can be scheduled as P2 but should still be included in the same patch cycle, because an attacker already on the perimeter will reuse the same primitive for lateral movement.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Upgrade yiisoft/yii2 to 2.0.52 or later via composer require yiisoft/yii2:^2.0.52 followed by composer update. Explicitly re-check deployments that lack a committed composer.lock.
      • Patch Craft CMS instances to a release that fixes CVE-2025-32432 (Craft 3.9.15, 4.14.15, 5.6.17 or newer) — image-transform endpoints are the known attack surface.
      • Inventory all PHP applications: grep -r "yiisoft/yii2" /var/www --include=composer.lock, plus a code review for Yii::createObject called with user-controllable config arrays in legacy code.
      • Place exposed Yii apps (admin, debug and image-transform endpoints in particular) behind authentication or VPN until the patch rollout is confirmed.
      • Run a compromise assessment for February-April 2025 and onwards: webshells under web/, assets/, runtime/, unexpected .php files with mtime after deployment, suspicious cron jobs, www-data shell history.
      • Rotate database and application credentials if any compromise indicator is found or if the application was internet-facing.

    2. Runbook step 2

      Mitigation layers

      • WAF rule: block HTTP requests whose JSON or form parameters contain a __class or class key inside nested arrays (regex example: (\"|%22)__class(\"|%22)\s*:). Apply particularly to POST bodies against image-transform and API endpoints.
      • Network segmentation: deny egress from PHP-FPM/web servers to arbitrary destinations — allowlist only backend services (DB, cache, SMTP). This defeats reverse shells and second-stage downloads.
      • Filesystem hardening: mount web/, assets/ and upload directories noexec, or exclude them from PHP execution in the web server config (<FilesMatch> on Apache, nginx location without fastcgi_pass).
      • PHP hardening: disable_functions = exec,passthru,shell_exec,system,proc_open,popen in php.ini, restrict open_basedir to the application directory, set expose_php = Off.
      • Least privilege: the web server account (www-data) must not have write access to code directories; only runtime/ and assets/ writable. Prefer immutable container images for deployment.
      • Disable Yii debug module (yii\debug\Module) and the Gii code generator in production, or restrict them to an IP allowlist.

    3. Runbook step 3

      Detection rules

      • Web access logs: search for __class in request bodies or query strings. Splunk: index=web sourcetype=access_combined "__class" — false-positive rate is low, triage any hit immediately.
      • Sysmon EID 1 / auditd execve: PHP-FPM or Apache process spawning sh, bash, curl, wget, python, perl, or nc. Sigma shape: ParentImage endswith 'php-fpm' AND Image in ('/bin/sh','/bin/bash','/usr/bin/curl').
      • File integrity: FIM alert (auditd -w /var/www -p wa) on new .php files outside the deployment window, especially under web/assets/ and runtime/.
      • Network telemetry (Zeek/Suricata): outbound connections from the web server segment to non-allowlisted destinations, in particular ports 4444, 1337, 8080 or paste-site / raw-GitHub domains.
      • Application log: Yii exceptions mentioning Unknown property or createObject correlated with unauthenticated requests — a strong signal of probing against the __class behavior vector.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Yii 2 before 2.0.52 mishandles the attaching of behavior that is defined by an __class array key, a CVE-2024-4990 regression, as exploited in the wild in February through April 2025.

    Source: pwn.watch, NVD (NIST), OSV (Open Source Vulnerabilities), CISA KEV Catalog, CVE.org (MITRE), cvelistv5

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    yiiframeworkYii
    • 2 – < 2.0.52
    • 2.0.52
    yiiframeworkyii
    • < 2.0.52
    • 2.0.52
    packagistyiisoft/yii2
    • 2.0.13.3
    • 2.0.16
    • 2.0.3
    • 2.0.35
    • 2.0.12.1
    • 2.0.33
    • 2.0.14.1
    • 2.0.34
    • 2.0.49.4
    • 2.0.12
    • 2.0.39.3
    • 2.0.4
    • 2.0.14.2
    • 2.0.13.1
    • 2.0.15
    • 2.0.13.2
    • 2.0.49.3
    • 2.0.25
    • 2.0.47
    • 2.0.50
    • 2.0.49
    • 2.0.27
    • 2.0.49.2
    • 2.0.5
    • 2.0.49.1
    • 2.0.15.1
    • 2.0.38
    • 2.0.24
    • 2.0.45
    • 2.0.37
    • 2.0.28
    • 2.0.8
    • 2.0.41.1
    • 2.0.6
    • 2.0.39.1
    • 2.0.23
    • 2.0.0-alpha
    • 2.0.9
    • 2.0.12.2
    • 2.0.26
    • 2.0.0-rc
    • 2.0.51
    • 2.0.1
    • 2.0.13
    • 2.0.42
    • 2.0.30
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    Vendors and products

    Weakness classes (CWE)

    • CWE-424Improper Protection of Alternate Path

      Class

      The product does not sufficiently protect all possible paths that a user can take to access restricted functionality or resources.

      Entry at MITRE CWE-424

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

    • NVD (NIST)NVD: CVE-2024-58136advisory, pwn-watch
    • github.comyiisoft/yii2/pull/20232web, Patch
    • github.comyiisoft/yii2/pull/20232web, Issue tracking
    • github.comyiisoft/yii2/commit/40fe496eda529fd1d933b56a1022ec32d3cd0b12web, Patch
    • github.comyiisoft/yii2package
    • github.comyiisoft/yii2/compare/2.0.51...2.0.52web, Issue tracking
    • sensepost.comblog/2025/investigating-an-in-the-wild-campaign-using-rce-in-cr…web
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2024-58136web, government-resource, US government resource
    • yiiframework.comYiiframework advisory: Yiiframework Yiiweb, Vendor advisory, pwn-watch
    • sensepost.comblog/2025/investigating-an-in-the-wild-campaign-using-rce-in-cr…Technical description, Exploit, Third-party advisory
    • pwn.watchpwn.watch: Yiiframework Yii: Yii Improper Protection of Alternate Path Vulnerabilitypwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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