Erlang OTP/Hex/Hex Core/Rebar3 Tar Extraction infinite loop

Summaryinfo

A vulnerability described as problematic has been identified in Erlang OTP, Hex, Hex Core and Rebar3. This vulnerability affects the function erl_tar:do_sparse_read/3/erl_tar:extract/1/erl_tar:extract/2/erl_tar:stream_to_file_loop/3 of the component Tar Extraction. Such manipulation leads to infinite loop. This vulnerability is documented as CVE-2026-96596. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Erlang OTP, Hex, Hex Core and Rebar3 (unknown version). It has been rated as problematic. Affected by this issue is the function erl_tar:do_sparse_read/3/erl_tar:extract/1/erl_tar:extract/2/erl_tar:stream_to_file_loop/3 of the component Tar Extraction. The manipulation with an unknown input leads to a infinite loop vulnerability. Using CWE to declare the problem leads to CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Impacted is availability. CVE summarizes:

Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in Erlang OTP stdlib (erl_tar module), hexpm hex_core (hex_erl_tar module), hexpm hex (mix_hex_erl_tar module) and erlang rebar3 (r3_hex_erl_tar module) allows an attacker who supplies a tar archive to cause a denial of service via a crafted GNU sparse member. When erl_tar:extract/1,2 writes a member to disk, erl_tar:stream_to_file_loop/3 reads it in chunks of 65536 bytes by default. For a GNU sparse member whose sparse map ends before its real size, erl_tar:do_sparse_read/3 matches its trailing-hole clause before its zero-length clause. After the chunk is used up, the trailing-hole clause reads zero bytes, does not advance the position, and recurses forever. A 2048-byte archive keeps the extracting process and one scheduler busy until the process is killed. The {max_size, N} option prevents this only when N is below the real size of the member. Extraction with the memory option is not affected. hex_core ships its own copy of erl_tar as hex_erl_tar, and Hex and rebar3 ship hex_core with prefixed module names (mix_hex_erl_tar and r3_hex_erl_tar). These copies contain the same code and do not call stdlib's erl_tar, so they are affected on any OTP version. OTP 28 is not affected, but an application running on OTP 28 is affected if it extracts archives through an affected version of hex_core, Hex or rebar3. This issue affects OTP from OTP 29.0 before OTP 29.1.2, corresponding to stdlib from 8.0 before 8.1.1, and rebar3 from 3.27.1 onward, and hex from 2.4.2 onward; hex_core: from 0.14.0 onward.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-96596 since 09/27/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-3964). Once again VulDB remains the best source for vulnerability data.

Affected

• Red Hat Enterprise Linux
• Open Source Erlang/OTP

Productinfo

Vendor

• Erlang

Name

• Hex
• Hex Core
• OTP
• Rebar3

Website

• Product: https://github.com/erlang/otp/

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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