A flaw was found in privoxy before 3.0.32. A invalid read of size two may occur in chunked_body_is_complete() leading to denial of service.

The version of privoxy installed on the remote host is prior to 3.0.23-2.17. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS-2023-1739 advisory.

  - A flaw was found in privoxy before 3.0.32. A invalid read of size two may occur in     chunked_body_is_complete() leading to denial of service. (CVE-2021-20275)

  - A vulnerability was found in Privoxy which was fixed in get_url_spec_param() by freeing memory of compiled     pattern spec before bailing. (CVE-2021-44540)

  - A memory leak vulnerability was found in Privoxy when handling errors. (CVE-2021-44542)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote host is affected by the vulnerability described in GLSA-202107-16 (Privoxy: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in privoxy. Please review       the CVE identifiers referenced below for details.
  Impact :

    An attacker could cause a possible Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4886-1 advisory.

    It was discovered that Privoxy incorrectly handled CGI requests. An attacker could possibly use this issue     to cause a denial of service or obtain sensitive information. (CVE-2020-35502, CVE-2021-20209,     CVE-2021-20210, CVE-2021-20213, CVE-2021-20215, CVE-2021-20216, CVE-2021-20217, CVE-2021-20272,     CVE-2021-20273, CVE-2021-20275)

    It was discovered that Privoxy incorrectly handled certain regular expressions. An attacker could possibly     use this issue to cause a denial of service or obtain sensitive information. (CVE-2021-20212,     CVE-2021-20276)

    It was discovered that Privoxy incorrectly handled client tags. An attacker could possibly use this issue     to cause Privoxy to consume resources, resulting in a denial of service. This issue only affected Ubuntu     18.04 LTS, Ubuntu 20.04 LTS and Ubuntu 20.10. (CVE-2021-20211)

    It was discovered that Privoxy incorrectly handled client tags. An attacker could possibly use this issue     to cause Privoxy to consume resources, resulting in a denial of service. This issue only affected Ubuntu     20.04 LTS and Ubuntu 20.10. (CVE-2021-20214)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

This update for privoxy fixes the following issues :

Update to version 3.0.32 :

  - Security/Reliability (boo#1183129)

  - ssplit(): Remove an assertion that could be triggered     with a crafted CGI request. Commit 2256d7b4d67.
    OVE-20210203-0001. CVE-2021-20272 Reported by: Joshua     Rogers (Opera)

  - cgi_send_banner(): Overrule invalid image types.
    Prevents a crash with a crafted CGI request if Privoxy     is toggled off. Commit e711c505c48. OVE-20210206-0001.
    CVE-2021-20273 Reported by: Joshua Rogers (Opera)

  - socks5_connect(): Don't try to send credentials when     none are configured. Fixes a crash due to a NULL pointer     dereference when the socks server misbehaves. Commit     85817cc55b9. OVE-20210207-0001. CVE-2021-20274 Reported     by: Joshua Rogers (Opera)

  - chunked_body_is_complete(): Prevent an invalid read of     size two. Commit a912ba7bc9c. OVE-20210205-0001.
    CVE-2021-20275 Reported by: Joshua Rogers (Opera)

  - Obsolete pcre: Prevent invalid memory accesses with an     invalid pattern passed to pcre_compile(). Note that the     obsolete pcre code is scheduled to be removed before the     3.0.33 release. There has been a warning since 2008     already. Commit 28512e5b624. OVE-20210222-0001.
    CVE-2021-20276 Reported by: Joshua Rogers (Opera)

  - Bug fixes :

  - Properly parse the client-tag-lifetime directive.
    Previously it was not accepted as an obsolete hash value     was being used. Reported by: Joshua Rogers (Opera)

  - decompress_iob(): Prevent reading of uninitialized data.
    Reported by: Joshua Rogers (Opera).

  - decompress_iob(): Don't advance cur past eod when     looking for the end of the file name and comment.

  - decompress_iob(): Cast value to unsigned char before     shifting. Prevents a left-shift of a negative value     which is undefined behaviour. Reported by: Joshua Rogers     (Opera)

  - gif_deanimate(): Confirm that that we have enough data     before doing any work. Fixes a crash when fuzzing with     an empty document. Reported by: Joshua Rogers (Opera).

  - buf_copy(): Fail if there's no data to write or nothing     to do. Prevents undefined behaviour 'applying zero     offset to NULL pointer'. Reported by: Joshua Rogers     (Opera)

  - log_error(): Treat LOG_LEVEL_FATAL as fatal even when
    --stfu is being used while fuzzing. Reported by: Joshua     Rogers (Opera).

  - Respect DESTDIR when considering whether or not to     install config files with '.new' extension.

  - OpenSSL ssl_store_cert(): Fix two error messages.

  - Fix a couple of format specifiers.

  - Silence compiler warnings when compiling with NDEBUG.

  - fuzz_server_header(): Fix compiler warning.

  - fuzz_client_header(): Fix compiler warning.

  - cgi_send_user_manual(): Also reject requests if the     user-manual directive specifies a https:// URL.
    Previously Privoxy would try and fail to open a local     file.

  - General improvements :

  - Log the TLS version and the the cipher when debug 2 is     enabled.

  - ssl_send_certificate_error(): Respect HEAD requests by     not sending a body.

  - ssl_send_certificate_error(): End the body with a single     new line.

  - serve(): Increase the chances that the host is logged     when closing a server socket.

  - handle_established_connection(): Add parentheses to     clarify an expression Suggested by: David Binderman

  - continue_https_chat(): Explicitly unset     CSP_FLAG_CLIENT_CONNECTION_KEEP_ALIVE if     process_encrypted_request() fails. This makes it more     obvious that the connection will not be reused.
    Previously serve() relied on     CSP_FLAG_SERVER_CONTENT_LENGTH_SET and CSP_FLAG_CHUNKED     being unset. Inspired by a patch from Joshua Rogers     (Opera).

  - decompress_iob(): Add periods to a couple of log     messages

  - Terminate the body of the HTTP snipplets with a single     new line instead of '\r\n'.

  - configure: Add --with-assertions option and only enable     assertions when it is used

  - windows build: Use --with-brotli and --with-mbedtls by     default and enable dynamic error checking.

  - gif_deanimate(): Confirm we've got an image before     trying to write it Saves a pointless buf_copy() call.

  - OpenSSL ssl_store_cert(): Remove a superfluous space     before the serial number.

  - Action file improvements :

  - Disable fast-redirects for .golem.de/

  - Unblock requests to adri*.

  - Block requests for trc*.taboola.com/

  - Disable fast-redirects for .linkedin.com/

  - Filter file improvements :

  - Make the second pcrs job of the img-reorder filter     greedy again. The ungreedy version broke the img tags     on: https://bulk.fefe.de/scalability/.

  - Privoxy-Log-Parser :

  - Highlight a few more messages.

  - Clarify the --statistics output. The shown 'Reused     connections' are server connections so name them     appropriately.

  - Bump version to 0.9.3.

  - Privoxy-Regression-Test :

  - Add the --check-bad-ssl option to the --help output.

  - Bump version to 0.7.3.

  - Documentation :

  - Add pushing the created tag to the release steps in the     developer manual.

  - Clarify that 'debug 32768' should be used in addition to     the other debug directives when reporting problems.

  - Add a 'Third-party licenses and copyrights' section to     the user manual.

Multiple vulnerabilites were discovered in privoxy, a web proxy with advanced filtering capabilities.

CVE-2021-20272

An assertion failure could be triggered with a crafted CGI request leading to server crash.

CVE-2021-20273

A crash can occur via a crafted CGI request if Privoxy is toggled off.

CVE-2021-20275

An invalid read of size two may occur in chunked_body_is_complete() leading to denial of service.

CVE-2021-20276

Invalid memory access with an invalid pattern passed to pcre_compile() may lead to denial of service.

For Debian 9 stretch, these problems have been fixed in version 3.0.26-3+deb9u2.

We recommend that you upgrade your privoxy packages.

For the detailed security status of privoxy please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/privoxy

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
175092	Amazon Linux AMI : privoxy (ALAS-2023-1739)	Nessus	Amazon Linux Local Security Checks	high
157017	GLSA-202107-16 : Privoxy: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
147971	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Privoxy vulnerabilities (USN-4886-1)	Nessus	Ubuntu Local Security Checks	high
147925	openSUSE Security Update : privoxy (openSUSE-2021-443)	Nessus	SuSE Local Security Checks	high
147548	Debian DLA-2587-1 : privoxy security update	Nessus	Debian Local Security Checks	high

Detections

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CVE-2021-20275

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Tenable Plugins

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