CVE-2018-20482 — GNU Tar through 1.30, when --sparse is used, mishandles file shrinkage during read access, which...
GNU Tar through 1.30, when --sparse is used, mishandles file shrinkage during read access, which allows local users to cause a denial of service (infinite read loop in sparse_dump_region in sparse.c) by modifying a file that is supposed to be archived by a different user's process (e.g., a system backup running as root).
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.5% (30-day exploitation probability)+7
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.savannah.gnu.org (NIST National Vulnerability Database)
- Documented patch — twitter.com (NIST National Vulnerability Database)
- Documented patch — utcc.utoronto.ca (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Debian Debian Linux, Gnu Tar, Opensuse Leap).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 4.7 | CVSS 3.1 | Medium | 1.0 | 3.6 | nvd@nist.gov via NIST National Vulnerability Database |
| 4.7 | CVSS 3.1 | Medium | — | — | GitHub, Inc. via GitHub Security Advisories |
| 1.9 | CVSS 2.0 | Low | 3.4 | 2.9 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.53%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Track CPU/memory spikes and availability drops correlated with request patterns.
Timeline
What happened to this CVE, newest first.
- 2026
- Record published
- Fix documented
- Affected products added · gnu/tar, debian/debian linux, opensuse/leap
- CVSS changed · 4.7
- Source status changed · → Modified
- Record created in this database
- 2018
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 14, 2026 – Oct 14, 2026
References
13 on the record
- twitter.com/thatcks/status/1076166645708668928
- utcc.utoronto.ca/~cks/space/blog/sysadmin/TarFindingTruncateBug
- git.savannah.gnu.org/cgit/tar.git/commit/
- security.gentoo.org/glsa/201903-05
- cert-portal.siemens.com/productcert/html/ssa-398330.html
- nvd.nist.gov/vuln/detail/CVE-2018-20482
- lists.opensuse.org/opensuse-security-announce/2019-04/msg00077.html
- lists.gnu.org/archive/html/bug-tar/2018-12/msg00023.html
- lists.debian.org/debian-lts-announce/2021/11/msg00025.html
- lists.debian.org/debian-lts-announce/2018/12/msg00023.html
- news.ycombinator.com/item
- github.com/advisories/GHSA-pm5x-48pq-67cq
- www.securityfocus.com/bid/106354
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-18477 TOCTOU Race Condition in Gnu Tar Aug 3, 2026
- Medium CVE-2026-18508 Link Following in Gnu Tar Aug 3, 2026
- High CVE-2026-12996 A use-after-free in OpenVPN 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows remote... Jul 30, 2026
- Medium CVE-2026-14355 ext/openssl: Memory corruption in openssl_encrypt with AES-WRAP-PAD Jul 3, 2026
- Medium CVE-2026-56968 Use of Uninitialized Resource in Gnu Sasl Jun 23, 2026
- High CVE-2026-49975 Apache HTTP Server: mod_http2 denial of service Jun 8, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2018-20482 is "GNU Tar through 1.30, when --sparse is used, mishandles file shrinkage during read access, which...", rated Medium. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.7 describes technical severity. EPSS 0.53% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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