Lighttpd: Missing Release of Memory after Effective Lifetime
CVE-2022-41556 is a high-severity missing release of memory after effective lifetime vulnerability in Lighttpd, 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 1.4.67 as the first without the flaw, so updating Lighttpd to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 3.83% chance of exploitation within 30 days, which is in the top 9.74% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Lighttpd to 1.4.67 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 |
|---|---|---|---|
| Lighttpd | Lighttpd | 1.4.56 up to, but not including, 1.4.67 | 1.4.67 |
| Fedora Project | Fedora | 35 | Not stated |
Version data comes from NVD's product matching. 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.
Official description
A resource leak in gw_backend.c in lighttpd 1.4.56 through 1.4.66 could lead to a denial of service (connection-slot exhaustion) after a large amount of anomalous TCP behavior by clients. It is related to RDHUP mishandling in certain HTTP/1.1 chunked situations. Use of mod_fastcgi is, for example, affected. This is fixed in 1.4.67.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Release of Memory after Effective Lifetime
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
How developers prevent this class of flaw
- Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC). To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.
More Missing Release of Memory after Effective Lifetime vulnerabilities (CWE-401)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.lighttpd.net/lighttpd/lighttpd1.4/commit/b18de6f9264f914f7bf493abd3b6059343548e50Third Party Advisory
- github.com/lighttpd/lighttpd1.4/pull/115Exploit, Issue Tracking, Third Party Advisory
Third-party and government advisories
- github.com/lighttpd/lighttpd1.4/compare/lighttpd-1.4.66...lighttpd-1.4.67Third Party Advisory
- security.gentoo.org/glsa/202210-12Third Party Advisory
Other references
Other vulnerabilities in Lighttpd
- 9.1 Critical severity
- 7.5 High severity
- 7.5 High severity
Recent Missing Release of Memory after Effective Lifetime vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.8 High severity
- 8.2 High severity
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