libksba: Integer Overflow or Wraparound
CVE-2022-3515 is a critical-severity integer overflow or wraparound vulnerability in libksba, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected libksba versions: Fixed in libksba v1.6.2. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.77% chance of exploitation within 30 days, higher than 78% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Gpg4win to 4.1.0 or a later version.
- Update Vs-desktop to 3.1.26 or a later version.
- Update Gnupg to 2.2.41 or 2.4.0, whichever matches your release line, 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 |
|---|---|---|---|
| Libksba | libksba | Fixed in libksba v1.6.2 | Not stated |
| Gpg4win | Gpg4win | 2.0.0 up to, but not including, 4.1.0 | 4.1.0 |
| Gnupg | Vs-desktop | 3.1.16 up to, but not including, 3.1.26 | 3.1.26 |
| Gnupg | Gnupg | 2.1.0 up to, but not including, 2.2.41; 2.3.0 up to, but not including, 2.4.0 | 2.2.41, 2.4.0 |
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
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 3.1 | 9.8 | Critical | CISA (ADP) |
Official description
A vulnerability was found in the Libksba library due to an integer overflow within the CRL parser. The vulnerability can be exploited remotely for code execution on the target system by passing specially crafted data to the application, for example, a malicious S/MIME attachment.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Overflow or Wraparound
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How developers prevent this class of flaw
- Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
More Integer Overflow or Wraparound vulnerabilities (CWE-190)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- access.redhat.com/security/cve/CVE-2022-3515Third Party Advisory
- dev.gnupg.org/rK4b7d9cd4a018898d7714ce06f3faf2626c14582bExploit, Third Party Advisory
Third-party and government advisories
- gnupg.org/blog/20221017-pepe-left-the-ksba.htmlThird Party Advisory
Technical write-ups (may include proof of concept)
- bugzilla.redhat.com/show_bug.cgi?id=2135610Exploit, Issue Tracking, Third Party Advisory
Other references
Recent Integer Overflow or Wraparound vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.1 High severity
- 8.8 High severity
- 7.1 High severity
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