netatalk: Off-by-one Error
CVE-2024-38440 is a high-severity off-by-one error vulnerability in netatalk, 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 3.2.1 as the first without the flaw, so updating netatalk to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.88% chance of exploitation within 30 days, higher than 60% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update netatalk to 3.2.1 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
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 CISA (ADP).
Official description
Netatalk before 3.2.1 has an off-by-one error, and resultant heap-based buffer overflow and segmentation violation, because of incorrectly using FPLoginExt in BN_bin2bn in etc/uams/uams_dhx_pam.c. The original issue 1097 report stated: 'The latest version of Netatalk (v3.2.0) contains a security vulnerability. This vulnerability arises due to a lack of validation for the length field after parsing user-provided data, leading to an out-of-bounds heap write of one byte (\0). Under specific configurations, this can result in reading metadata of the next heap block, potentially causing a Denial of Service (DoS) under certain heap layouts or with ASAN enabled. ... The vulnerability is located in the FPLoginExt operation of Netatalk, in the BN_bin2bn function found in /etc/uams/uams_dhx_pam.c ... if (!(bn = BN_bin2bn((unsigned char *)ibuf, KEYSIZE, NULL))) ... threads ... [#0] Id 1, Name: "afpd", stopped 0x7ffff4304e58 in ?? (), reason: SIGSEGV ... [#0] 0x7ffff4304e58 mov BYTE PTR [r14+0x8], 0x0 ... mov rdx, QWORD PTR [rsp+0x18] ... afp_login_ext(obj=<optimized out>, ibuf=0x62d000010424 "", ibuflen=0xffffffffffff0015, rbuf=<optimized out>, rbuflen=<optimized out>) ... afp_over_dsi(obj=0x5555556154c0 <obj>).' 2.4.1 and 3.1.19 are also fixed versions.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Off-by-one Error
A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.
How developers prevent this class of flaw
- When copying character arrays or using character manipulation methods, the correct size parameter must be used to account for the null terminator that needs to be added at the end of the array. Some examples of functions susceptible to this weakness in C include strcpy(), strncpy(), strcat(), strncat(), printf(), sprintf(), scanf() and sscanf().
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
Advisories
Other references
Other vulnerabilities in netatalk
- 7.5 High severity
- 7.5 High severity
- 7.6 High severity
- 7.1 High severity
- 7.1 High severity
- 7.5 High severity
Recent Off-by-one Error vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.8 High severity
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