Coordinated Disclosure Timeline
- 2021-08-31: Sent report to email@example.com (@valenad1)
- 2021-10-18: Resent the report to firstname.lastname@example.org. (They recently added a
- 2021-10-18: Received automated response with ticket ID 100579.
- 2021-10-19: Reply from H2O Support: “We created a Bug Fix Request to our Engineering Team. We will update you once we have news from them.”
- 2021-10-22: Bug is fixed.
- 2021-10-25: Email from H2O Support: “Resolution will be part of next release 18.104.22.168, unfortunately we can not confirm release date yet.”
- 2022-01-04: Email from H2O Support: “Sorry for delay in response, There is already a 3.36 release available for download.”
H2O contains a regular expression that is vulnerable to ReDoS (Regular Expression Denial of Service).
ReDoS, or Regular Expression Denial of Service, is a vulnerability affecting inefficient regular expressions which can perform extremely badly when run on a crafted input string.
This vulnerability was found using a CodeQL query which identifies inefficient regular expressions.
The vulnerable regular expression is here.
To see that the regular expression is vulnerable, copy-paste it into a separate file as shown below:
- Run the code below with
import re reg = re.compile('(?:.*,)*\s*Negotiate\s*([^,]*),?', re.I); reg.match(",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Negotiaet,"); # `Negotiate` is misspelled on purpose, to make sure the regexp doesn't match.
This issue may lead to a denial of service.
This issue was discovered by GitHub team members @erik-krogh (Erik Krogh Kristensen) and @yoff (Rasmus Petersen).
You can contact the GHSL team at
email@example.com, please include a reference to
GHSL-2021-119 in any communication regarding this issue.