PSF-2019-14 Regular Expression Denial of Service in http.cookiejar

Not scored Published

A malicious HTTP server can cause extreme CPU usage and block execution in Python applications parsing Set-Cookie headers via a vulnerable regex.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Over the internet
Victim action needed
Not needed
Fix
None listed

What is PSF-2019-14?

PSF-2019-14 is a denial of service vulnerability, published on 14 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The regex http.cookiejar.LOOSE_HTTP_DATE_RE is vulnerable to regular expression denial of service ("REDoS"). LOOSE_HTTP_DATE_RE.match() is called when using http.cookiejar.CookieJar to parse Set-Cookie headers returned by a HTTP server. Processing a response from a malicious HTTP server can lead to extreme CPU usage and execution will be blocked for a long time.

Which versions are affected by PSF-2019-14?

How do I fix PSF-2019-14?

No fix has been published for PSF-2019-14 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is PSF-2019-14 being exploited?

There is no known exploitation of PSF-2019-14 in the wild and no public exploit code.

Sources

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