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GHSA-wpqr-jcpx-745r
No affected components available
Impact
What kind of vulnerability is it? Who is impacted?
Anyone parsing JSON from an untrusted source is vulnerable.
JSON strings that contain escaped surrogate characters not part of a proper surrogate pair were decoded incorrectly. Besides corrupting strings, this allowed for potential key confusion and value overwriting in dictionaries.
Examples:
# An unpaired high surrogate character is ignored.
>>> ujson.loads(r'"\uD800"')
''
>>> ujson.loads(r'"\uD800hello"')
'hello'
# An unpaired low surrogate character is preserved.
>>> ujson.loads(r'"\uDC00"')
'\udc00'
# A pair of surrogates with additional non surrogate characters pair up in spite of being invalid.
>>> ujson.loads(r'"\uD800foo bar\uDC00"')
'foo bar𐀀'
Patches
Has the problem been patched? What versions should users upgrade to?
Users should upgrade to UltraJSON 5.4.0.
From version 5.4.0, UltraJSON decodes lone surrogates in the same way as the standard library's json module does, preserving them in the parsed output:
>>> ujson.loads(r'"\uD800"')
'\ud800'
>>> ujson.loads(r'"\uD800hello"')
'\ud800hello'
>>> ujson.loads(r'"\uDC00"')
'\udc00'
>>> ujson.loads(r'"\uD800foo bar\uDC00"')
'\ud800foo bar\udc00'
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
Short of switching to an entirely different JSON library, there are no safe alternatives to upgrading.
For more information
If you have any questions or comments about this advisory:
- Open an issue in UltraJSON
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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