CVE-2021-29482: denial of service in github.com/ulikunitz/xz
Vulnerability summary
CVE-2021-29482 is a high (CVSS 7.5) Loop with Unreachable Exit Condition vulnerability in ulikunitz xz. EPSS estimates a 1.44% chance of exploitation in the next 30 days, higher than 73.1% of scored vulnerabilities.
Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 1Timeline
- 28-04-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
xz is a compression and decompression library focusing on the xz format completely written in Go. The function readUvarint used to read the xz container format may not terminate a loop provide malicous input. The problem has been fixed in release v0.5.8. As a workaround users can limit the size of the compressed file input to a reasonable size for their use case. The standard library had recently the same issue and got the CVE-2020-16845 allocated.
CVSS metrics
6 scores · 5 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · GoEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
1.44%
Chance of exploitation in the next 30 days
Percentile
73%
Versus all other CVEs
30-day change
No change 0.00 pp
From 1.44% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Debian1 product
- golang-github-ulikunitz-xz< 0.5.6-2
Github.com/ulikunitz1 product
- xz< 0.5.8
Ubuntu1 product
- golang-github-ulikunitz-xzAll versions (No fix recorded)
Ulikunitz1 product
- xz< 0.5.8
Xz_project1 product
- xz< 0.5.8
5 vendors · 5 products
References
8 links- github.com/ulikunitz/xz/security/advisories/GHSA-25xm-hr59-7c27X Refsource CONFIRMREPORTWEBThird Party Advisory
- github.com/ulikunitz/xz/commit/69c6093c7b2397b923acf82cb378f55ab2652b9bX Refsource MISCREPORTWEBFIXPatchThird Party Advisory
