squid: Uncontrolled Recursion
CVE-2024-25111 is a high-severity uncontrolled recursion vulnerability in squid from Squid-cache, 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 6.8 as the first without the flaw, so updating squid to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 65.3% chance of exploitation within 30 days, which is in the top 0.73% of all scored CVEs.
Exploitation in the next 30 days is more likely than not, according to EPSS.
What to do
- Update squid to 6.8 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| Squid-cache | squid | >= 3.5.27, < 6.8; 3.5.27 up to, but not including, 6.8 | 6.8 |
| NetApp | bluexp | all versions | Not stated |
| Fedora Project | fedora | 38; 39 | Not stated |
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 | 8.6 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
Squid is a web proxy cache. Starting in version 3.5.27 and prior to version 6.8, Squid may be vulnerable to a Denial of Service attack against HTTP Chunked decoder due to an uncontrolled recursion bug. This problem allows a remote attacker to cause Denial of Service when sending a crafted, chunked, encoded HTTP Message. This bug is fixed in Squid version 6.8. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. There is no workaround for this issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Uncontrolled Recursion
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
How developers prevent this class of flaw
- Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- squid-cache.org/Versions/v6/SQUID-2024_1.patchMailing List
Third-party and government advisories
- security.netapp.com/advisory/ntap-20240605-0001/Third Party Advisory
Other references
Other vulnerabilities in squid
- 7.7 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
Recent Uncontrolled Recursion 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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