# CVE-2020-27874: Memory corruption in WeChat

> Remote attackers can execute arbitrary code in WeChat by tricking users into visiting malicious pages or opening files due to a memory corruption flaw in the WXAM Decoder.

- **Severity:** High 8.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 10 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-6c98-7x6w-rx39

## What is CVE-2020-27874?

CVE-2020-27874 is a high-severity memory corruption vulnerability in Tencent WeChat, published on 10 Feb 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Tencent WeChat 7.0.18. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the WXAM Decoder. The issue results from the lack of proper validation of user-supplied data, which can result in a memory access past the end of an allocated object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-11580.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2020-27874?

It affects 1 product.


Products: Tencent Wechat.

## How do I fix CVE-2020-27874?

No fix has been published for CVE-2020-27874 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-27874 being exploited?

There is no known exploitation of CVE-2020-27874 in the wild and no public exploit code.

## Other vulnerabilities in Tencent WeChat

- [CVE-2024-40433](https://insights.sbomify.com/CVE-2024-40433/): Privilege escalation in n/a (high 8.8)
- [CVE-2021-40180](https://insights.sbomify.com/CVE-2021-40180/): Information disclosure in n/a (high 7.5)
- [CVE-2021-27247](https://insights.sbomify.com/CVE-2021-27247/): Information disclosure in WeChat (medium 6.5)
- [CVE-2019-11419](https://insights.sbomify.com/CVE-2019-11419/): Null dereference in n/a (medium 5.5)
- [CVE-2019-17151](https://insights.sbomify.com/CVE-2019-17151/): Open redirect in WeChat (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-27874 and fix it if it is affected.

What it is: CVE-2020-27874 is a high-severity memory corruption vulnerability in Tencent WeChat, published on 10 Feb 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-27874 in the wild and no public exploit code.

Affected product: Tencent WeChat. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-27874/ (Markdown: https://insights.sbomify.com/CVE-2020-27874/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27874
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27874
- OSV: https://osv.dev/vulnerability/CVE-2020-27874

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-27874/
Summaries are generated and may contain mistakes; the official description above is the record.