oss-security - CVE-2017-15710: Out of bound write in mod_authnz_ldap when using too small Accept-Language values

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Message-Id: <E1ezZFn-00031E-TI@romulus.home.bitnebula.com>
Date: Fri, 23 Mar 2018 21:49:59 -0500
From: Daniel Ruggeri <druggeri@...che.org>
To: announce@...pd.apache.org, oss-security@...ts.openwall.com,
    security@...pd.apache.org
Subject: CVE-2017-15710: Out of bound write in mod_authnz_ldap when using too small Accept-Language values

CVE-2017-15710: Out of bound write in mod_authnz_ldap when using too small Accept-Language values.

Severity: Low

Vendor: The Apache Software Foundation

Versions Affected:
httpd 2.0.23 to 2.0.65
httpd 2.2.0 to 2.2.34
httpd 2.4.0 to 2.4.29

Description:

mod_authnz_ldap, if configured with AuthLDAPCharsetConfig,
uses the Accept-Language header value to lookup the right charset encoding
when verifying the user's credentials.
If the header value is not present in the charset conversion
table, a fallback mechanism is used to truncate it to a two
characters value to allow a quick retry (for example, 'en-US' is truncated
to 'en'). A header value of less than two characters forces an out of bound
write of one NUL byte to a memory location that is not part of the string.
In the worst case, quite unlikely, the process would crash which could
be used as a Denial of Service attack. In the more likely case, this memory is
already reserved for future use and the issue has no effect at all."

Mitigation:
All httpd users should upgrade to 2.4.30 or later.

Users of (the now end-of-life) httpd 2.2 who cannot upgrade at this time should
apply CVE-2017-15710.patch, which is available at

   https://www.apache.org/dist/httpd/patches/apply_to_2.2.34/

Credit:
The Apache HTTP Server security team would like to thank Alex Nichols
and Jakob Hirsch for reporting this issue.

References:
https://httpd.apache.org/security/vulnerabilities_24.html

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