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CVE-2023-36478: Issue #9554 - move common hpack/qpack code to jetty-http (jetty-10) by lachlan-roberts · Pull Request #9634 · eclipse/jetty.project
Eclipse Jetty provides a web server and servlet container. In versions 11.0.0 through 11.0.15, 10.0.0 through 10.0.15, and 9.0.0 through 9.4.52, an integer overflow in MetaDataBuilder.checkSize allows for HTTP/2 HPACK header values to
exceed their size limit. MetaDataBuilder.java determines if a header name or value exceeds the size limit, and throws an exception if the limit is exceeded. However, when length is very large and huffman is true, the multiplication by 4 in line 295
will overflow, and length will become negative. (_size+length) will now be negative, and the check on line 296 will not be triggered. Furthermore, MetaDataBuilder.checkSize allows for user-entered HPACK header value sizes to be negative, potentially leading to a very large buffer allocation later on when the user-entered size is multiplied by 2. This means that if a user provides a negative length value (or, more precisely, a length value which, when multiplied by the 4/3 fudge factor, is negative), and this length value is a very large positive number when multiplied by 2, then the user can cause a very large buffer to be allocated on the server. Users of HTTP/2 can be impacted by a remote denial of service attack. The issue has been fixed in versions 11.0.16, 10.0.16, and 9.4.53. There are no known workarounds.
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An integer overflow in `MetaDataBuilder.checkSize` allows for HTTP/2 HPACK header values to exceed their size limit. In `MetaDataBuilder.java`, the following code determines if a header name or value exceeds the size limit, and throws an exception if the limit is exceeded: ```java 291 public void checkSize(int length, boolean huffman) throws SessionException 292 { 293 // Apply a huffman fudge factor 294 if (huffman) 295 length = (length * 4) / 3; 296 if ((_size + length) > _maxSize) 297 throw new HpackException.SessionException("Header too large %d > %d", _size + length, _maxSize); 298 } ``` However, when length is very large and huffman is true, the multiplication by 4 in line 295 will overflow, and length will become negative. (_size+length) will now be negative, and the check on line 296 will not be triggered. Furthermore, `MetaDataBuilder.checkSize` allows for user-entered HPACK header value sizes to be negative, potentially leading to a very large buffer allocation later on w...