# What is CVE-2023-42503? > CVE-2023-42503 is a medium-severity flaw (CVSS 5.5) in Commons Compress from Apache, published on 14 September 2023. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 0.6%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2023-42503 ## At a glance - **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle. - **Precursor Intelligence risk score:** 18 out of 100 (Info); action: Track. Kept up to date as the evidence changes. - **Severity:** Medium (CVSS 5.5 out of 10) - **Known to be exploited:** No, not on the list of flaws known to be exploited today - **Chance of use in the next 30 days:** 0.6% (latest exploit-likelihood forecast) - **Published:** 14 September 2023 - **Record last updated:** 13 February 2025 - **Main product:** Commons Compress from Apache - **Affected products:** 1 ## What is CVE-2023-42503? In plain terms An attacker has to be already on the device without logging in, but a person has to take an action first. If it works, the attacker can take it offline. ### The official description Improper Input Validation, Uncontrolled Resource Consumption vulnerability in Apache Commons Compress in TAR parsing.This issue affects Apache Commons Compress: from 1.22 before 1.24.0. Users are recommended to upgrade to version 1.24.0, which fixes the issue. A third party can create a malformed TAR file by manipulating file modification times headers, which when parsed with Apache Commons Compress, will cause a denial of service issue via CPU consumption. In version 1.22 of Apache Commons Compress, support was added for file modification times with higher precision (issue # COMPRESS-612 [1]). The format for the PAX extended headers carrying this data consists of two numbers separated by a period [2], indicating seconds and subsecond precision (for example “1647221103.5998539”). The impacted fields are “atime”, “ctime”, “mtime” and “LIBARCHIVE.creationtime”. No input validation is performed prior to the parsing of header values. Parsing of these numbers uses the BigDecimal [3] class from the JDK which has a publicly known algorithmic complexity issue when doing operations on large numbers, causing denial of service (see issue # JDK-6560193 [4]). A third party can manipulate file time headers in a TAR file by placing a number with a very long fraction (300,000 digits) or a number with exponent notation (such as “9e9999999”) within a file modification time header, and the parsing of files with these headers will take hours instead of seconds, leading to a denial of service via exhaustion of CPU resources. This issue is similar to CVE-2012-2098 [5]. [1]: https://issues.apache.org/jira/browse/COMPRESS-612 [2]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_05 [3]: https://docs.oracle.com/javase/8/docs/api/java/math/BigDecimal.html [4]: https://bugs.openjdk.org/browse/JDK-6560193 [5]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-2098 Only applications using CompressorStreamFactory class (with auto-detection of file types), TarArchiveInputStream and TarFile classes to parse TAR files are impacted. Since this code was introduced in v1.22, only that version and later versions are impacted. ### What kind of flaw is it? - CWE-20: Improper Input Validation - CWE-400: Uncontrolled Resource Consumption ### How an attack on it works - Where an attacker can be: Already on the device - How hard it is to pull off: Easy: no special conditions - Login needed first: No login needed - Does someone have to click: Yes, a person has to take an action - What an attacker gets: Can take it offline Severity vector: `CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H` ## Is CVE-2023-42503 being exploited? Not that we know of It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.6%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: 0.6%, 0.6%, 0.6%, 0.6%, 0.6%, 0.6%, 0.6%. ### Timeline - 14 September 2023: Published - 13 February 2025: Record last updated ### How Precursor Intelligence ranks it CVE-2023-42503 scores **18 out of 100 (Info)**, with the action "Track". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2023-42503? The published record lists 1 product. Versions are as published: "1.22 to before 1.24.0" means from 1.22 up to, but not including, 1.24.0. - [Commons Compress](https://www.precursorintelligence.com/product/apache/commons_compress) by [Apache](https://www.precursorintelligence.com/vendors/apache) (Application): 1.22 to before 1.24.0 ## How do I fix CVE-2023-42503? 1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list. 2. **Apply the vendor’s fix.** Install the latest update from the vendor. The references list where the vendor has published details. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood. ### References - [lists.apache.org](https://lists.apache.org/thread/5xwcyr600mn074vgxq92tjssrchmc93c) (Issue tracking, Mailing list, Url repurposed) - [security.netapp.com](https://security.netapp.com/advisory/ntap-20231020-0003/) (Third-party advisory) ## Questions ### What is CVE-2023-42503? CVE-2023-42503 is a medium-severity flaw in Commons Compress from Apache, published on 14 September 2023. An attacker has to be already on the device without logging in, but a person has to take an action first. If it works, the attacker can take it offline. ### How serious is CVE-2023-42503? It scores 5.5 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2023-42503 is 18 out of 100, which is Info. Its action is "Track". No sign of exploitation and a low forecast. Patch it in your normal update cycle. ### Is CVE-2023-42503 being exploited? It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.6%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2023-42503 affect? For Commons Compress from Apache: 1.22 to before 1.24.0. ### How do I fix CVE-2023-42503? Install the update the vendor names in its advisory. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. ## Does CVE-2023-42503 affect you? 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