CVE-2020-6838
CVE-2020-6838 is a critical-severity vulnerability in Mruby with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v2: 7.5
- EPSS exploit prediction: 1% (71st percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-416
- Affected product: Mruby
- Published:
- Last modified:
Description
In mruby 2.1.0, there is a use-after-free in hash_values_at in mrbgems/mruby-hash-ext/src/hash-ext.c.
Frequently asked questions
- What is CVE-2020-6838?
- In mruby 2.1.0, there is a use-after-free in hash_values_at in mrbgems/mruby-hash-ext/src/hash-ext.c.
- How severe is CVE-2020-6838?
- CVE-2020-6838 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2020-6838 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2020-6838?
- CVE-2020-6838 affects Mruby. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2020-6838?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2020-6838 published?
- CVE-2020-6838 was published on 2020-01-11 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:mruby:mruby:2.1.0:*:*:*:*:*:*:*
More vulnerabilities in Mruby
- CVE-2022-1286 — Critical (CVSS 9.8): heap-buffer-overflow in mrb_vm_exec in mruby/mruby in GitHub repository mruby/mruby prior to 3.2. Possible arbitrary…
- CVE-2022-1276 — Critical (CVSS 9.8): Out-of-bounds Read in mrb_get_args in GitHub repository mruby/mruby prior to 3.2. Possible arbitrary code execution if…
- CVE-2022-1212 — Critical (CVSS 9.8): Use-After-Free in str_escape in mruby/mruby in GitHub repository mruby/mruby prior to 3.2. Possible arbitrary code…
- CVE-2022-0631 — Critical (CVSS 9.8): Heap-based Buffer Overflow in Homebrew mruby prior to 3.2.
- CVE-2022-0570 — Critical (CVSS 9.8): Heap-based Buffer Overflow in Homebrew mruby prior to 3.2.
- CVE-2022-0080 — Critical (CVSS 9.8): mruby is vulnerable to Heap-based Buffer Overflow
Other CWE-416 (Use After Free) vulnerabilities
- CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
- CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
- CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
- CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
- CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
- CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…