GHSA-3pv8-6f4r-ffg2
tar has a PAX header desynchronization issue
Blast Radius
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Description
Summary
When a tar stream contains multiple "header" entries prior to a file entry, tar-rs applies the PAX header (x) to the next entry in the stream, regardless of type. For example, a stream of x -> L -> file (PAX, GNU longname, file) would result in x's extensions being applied to L rather than to file.
Per POSIX pax, this is incorrect: a PAX header always applies to a file entry, not any intermediary entries. See the "pax Header Block" section for the specific prescription there.
As a result of this, an attacker can contrive a tar containing a sequence of tar headers such that tar-rs applies the PAX header's size extension to the next header in sequence, effectively desynchronizing the stream and enabling tar-rs specific skippage/extraction of members. In other words, a file can be contrived to extract differently on tar-rs than on other tar parsers.
PoC
This tar (zipped for size) demonstrates the desynchronization: with tar tvf:
% tar tvf tests/archives/pax-overrides-extension-header.tar
---------- 0 0 0 2048 Dec 31 1969 longname.txt
---------- 0 0 0 0 Dec 31 1969 file_b
with tar-rs:
---- pax_size_does_not_apply_to_extension_headers stdout ----
thread 'pax_size_does_not_apply_to_extension_headers' (250476889) panicked at tests/all.rs:2121:27:
called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "numeric field was not a number: AAAAAAAA when getting cksum for AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
In the above case, the PoC is not weaponized, so it jumps into the middle of an entry and subsequently fails the checksum test rather than silently continuing with attacker-controlled archive state.
Impact
This is very similar to GHSA-j5gw-2vrg-8fgx and GHSA-fp55-jw48-c537 in impact -- an attacker can use this to extract (or not extract) files from a tar stream depending on the tar parser used, which in turn can be used to obscure the presence of malicious files.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | tar | all versions | 0.4.46 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tar. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update tar to 0.4.46 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3pv8-6f4r-ffg2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-3pv8-6f4r-ffg2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-3pv8-6f4r-ffg2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-3pv8-6f4r-ffg2 in your dependencies?
O3 detects GHSA-3pv8-6f4r-ffg2 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.