http-cache-semantics: Inefficient Regular Expression Complexity
CVE-2022-25881 is a high-severity inefficient regular expression complexity vulnerability in http-cache-semantics, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 4.1.1 as the first without the flaw, so updating http-cache-semantics to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.66% chance of exploitation within 30 days, higher than 77% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update http-cache-semantics to 4.1.1 or a later version.
- Update org.webjars.npm:http-cache-semantics to 4.1.1 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Http-cache-semantics | http-cache-semantics | before 4.1.1 | 4.1.1 |
| Org.webjars.npm:http-cache-semantics | org.webjars.npm:http-cache-semantics | before 4.1.1 | 4.1.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.3 | Medium | CNA (snyk.io) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
This affects versions of the package http-cache-semantics before 4.1.1. The issue can be exploited via malicious request header values sent to a server, when that server reads the cache policy from the request using this library.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Inefficient Regular Expression Complexity
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
How developers prevent this class of flaw
- Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
- Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
- Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
More Inefficient Regular Expression Complexity vulnerabilities (CWE-1333)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-3253332Exploit, Third Party Advisory
- security.snyk.io/vuln/SNYK-JS-HTTPCACHESEMANTICS-3248783Exploit, Third Party Advisory
Other references
Recent Inefficient Regular Expression Complexity vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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