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FedoraOperating system · Fedoraproject

CVE-2023-31137

HIGH · 7.5 CVSS v3.1 Published 2023-05-09
Fix available
A fix is available. Upgrade to 3.4.10 / 3.5.0036 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 37= 38
Debian LinuxOperating system
Affected:= 10.0= 11.0
MaradnsApplication
Affected:< 3.4.10>= 3.5.0001, < 3.5.0036

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.4.10 / 3.5.0036 or later
Fixed in 3.4.103.5.0036
Vendor patch github.com →
Recommended fix High confidence

MaraDNS 3.5.0036 (or 3.4.10+ for the 3.4.x branch)

  1. 1. Identify the currently installed MaraDNS version using your system's package manager (e.g., `dnf info maradns` on Fedora, `dpkg -l maradns` on Debian).
  2. 2. For Fedora 37 and 38: Update the package to the latest available version which includes the fix in version 3.5.0036 or later.
  3. 3. For Debian 10.0 and 11.0: Update the package to the latest available version which includes the fix.
  4. 4. For MaraDNS 3.5.x versions: Upgrade to version 3.5.0036 or later which contains the patch from commit bab062bde40b2ae8a91eecd522e84d8b993bab58.
  5. 5. For MaraDNS versions below 3.4.10: Upgrade to version 3.4.10 or later (which should include the same fix).
  6. 6. After upgrading, restart the MaraDNS service to apply the changes.
  7. 7. Verify the new version is running using `maradns -v` or your system's service status command.
Caveat Review release notes for any configuration or feature changes between your current version and the upgrade version

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-31137 in production — separate from our analysis above.

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