CVE-2023-31137
Description
MaraDNS is open-source software that implements the Domain Name System (DNS). In version 3.5.0024 and prior, a remotely exploitable integer underflow vulnerability in the DNS packet decompression function allows an attacker to cause a Denial of Service by triggering an abnormal program termination. The vulnerability exists in the `decomp_get_rddata` function within the `Decompress.c` file. When handling a DNS packet with an Answer RR of qtype 16 (TXT record) and any qclass, if the `rdlength` is smaller than `rdata`, the result of the line `Decompress.c:886` is a negative number `len = rdlength - total;`. This value is then passed to the `decomp_append_bytes` function without proper validation, causing the program to attempt to allocate a massive chunk of memory that is impossible to allocate. Consequently, the program exits with an error code of 64, causing a Denial of Service. One proposed fix for this vulnerability is to patch `Decompress.c:887` by breaking `if(len <= 0)`, which has been incorporated in version 3.5.0036 via commit bab062bde40b2ae8a91eecd522e84d8b993bab58.
How to fix
- maradns maradns3.4.10, 3.5.0036 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| maradns maradns | v < 3.4.10, 3.5.0001 ≤ v < 3.5.0036 | 3.4.10, 3.5.0036 |
| fedoraproject fedora | 37, 38 | — |
| debian debian_linux | 10.0, 11.0 | — |
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