CVE-2026-53600 — async-tar PAX extension-header desync enables tar entry/content smuggling
async-tar is a tar archive reading/writing library for async Rust. Prior to version 0.6.1, async-tar mis-applies a buffered PAX size extension to an intermediary extension header (a GNU longname L, a GNU longlink K, or a PAX x/g header) instead of to the next file entry. POSIX requires a PAX extended-header record set to describe the next file entry, never an intervening extension header. Because poll_next_raw (src/archive.rs) threads the buffered PAX records into the size computation of whatever raw header it reads next — and that header can be an intermediary L — the stream cursor is advanced by an attacker-chosen amount when the L body is consumed. The parser then desyncs relative to a POSIX-correct tar parser (e.g. GNU tar), reading subsequent bytes at the wrong block boundary. This issue has been patched in version 0.6.1.
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
- Technical severity (medium)+3
- CISA SSVC: exploitation "poc"+5
- Automatable exploitation (SSVC)+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.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
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 (Dignifiedquire Async-tar).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (input validation), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Dignifiedquire | Async-tar | version < 0.6.1 | Vulnerable | CVE Program (cve.org) e CISA ADP |
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 |
|---|---|---|---|---|---|
| 6.3 | CVSS 4.0 | Medium | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 6.3 | CVSS 4.0 | Medium | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · dignifiedquire/async-tar
- SSVC assessment updated
- Record published
- CVSS changed · 6.3
- Source status changed · → Deferred
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
2 on the record
Elsewhere on this site
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 FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- 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-2026-53600 is "async-tar PAX extension-header desync enables tar entry/content smuggling", rated Medium. It affects Async-tar (Dignifiedquire); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.3 describes technical severity. 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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