OTP vulnerability

What happened

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 before 2.5.3; hex_core: from 0.14.0 before 0.20.1.

Affected versions

OTP: 29.0 through before 29.1.2 (otp); 8.0 through before 8.1.1 (otp); fbf2c7194f6fce4b7b66dc0bcaa4f6b4b85e088f through before 3086307f311b78b38644a7787a3aca6a3f95a9d5 (git); 3.27.1 through before * (semver); 23dbdb5d1f87f56902aef296c88a20049cd0c6e4 through before 310e2ec8c7dd3df05d67af2b7fae23f30fc523c4 (git); 0.14.0 through before 0.20.1 (semver); 13bb9fbba418a406af614790b8d5cd458259ee70 through before a2ece683e6e88a3ec95ad20b09aca426e08b372e (git); 2.4.2 through before 2.5.3 (semver); 5543a1919c709d8eb2b317f62aad76ca1eed375c through before * (git) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.