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CVE-2023-31137

HIGHCVSS 7.5/10EPSS 1.14%

Last modified

CVE-2023-31137 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 1.14% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
1.14%

62.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
MaradnsMaradns< 3.4.10
MaradnsMaradns>= 3.5.0001, < 3.5.0036
FedoraprojectFedora37
FedoraprojectFedora38
DebianDebian Linux10.0
DebianDebian Linux11.0

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2023-31137?
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 severe is CVE-2023-31137?
CVE-2023-31137 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.14% probability of exploitation in the next 30 days.
How do I fix CVE-2023-31137?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-31137?

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Source: NVD / NIST