Critical Memory Disclosure Vulnerability in Varnish HTTP Cache
Summary
ALPINE-CVE-2017-8807: vbf_stp_error in bin/varnishd/cache/cache_fetch.c in Varnish HTTP Cache 4.1.x before 4.1.9 and 5.x before 5.2.1 allows remote attackers to obtain sensitive information from process memory because a VFP_GetStorage buffer... Affects varnish versions < 5.2.1-r0. Fixed in 5.2.1-r0. How to fix ↓
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Background
Varnish is a powerful HTTP accelerator designed for high-performance web applications. It acts as a reverse proxy, caching content to reduce server load and improve response times. Varnish is widely used in various environments due to its flexibility and efficiency. However, it has been found to have a critical vulnerability that allows remote attackers to access sensitive information from process memory.
Vulnerability Detail
The vulnerability, identified as CVE-2017-8807, originates from a flaw in the vbf_stp_error function within the cache_fetch.c file of Varnish HTTP Cache versions prior to 4.1.9 and 5.x before 5.2.1. This issue arises when a VFP_GetStorage buffer is larger than intended, particularly in scenarios involving -sfile Stevedore transient objects. As a result, remote attackers can exploit this vulnerability to obtain sensitive information, potentially leading to data breaches and unauthorized access to critical system data. The CVSS score for this vulnerability is 9.1, indicating a high severity level.
How To Fix
Minimum fixed version
5.2.1-r0
This is the first release that contains the fix.
sudo apk add --upgrade varnishTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can limit access to the Varnish server by implementing firewall rules to restrict incoming connections. This may help mitigate the risk of exploitation until the package can be updated.
Conclusion
The vulnerability CVE-2017-8807 in Varnish HTTP Cache poses a significant risk due to its potential for memory disclosure. It is crucial for users to update their installations to the patched version to safeguard against possible exploitation. Implementing workarounds can provide temporary relief, but a full update is the recommended course of action.
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FAQ
CVE-2017-8807 is a critical vulnerability in Varnish HTTP Cache that allows remote attackers to access sensitive information from process memory.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
Exploitation of this vulnerability can lead to unauthorized access to sensitive data, potentially resulting in data breaches and loss of confidentiality.
If an immediate update is not possible, consider implementing firewall rules to restrict access to the Varnish server as a temporary workaround.
For more information about Varnish and its features, you can visit the official Varnish website or refer to the documentation provided by the Varnish community.
References
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